Anyways, here's my addition to this thread.
Brace yourself for this, Chicago has now entered the building
- I'll post by city limits then metro then companies with presence in the metro
Chicago City Limits:
Aon Corporation (ranked #298 on the 2010 Fortune 500 list)
A.T. Kearney
Bally Total Fitness
Boeing (ranked #28 on the 2010 Fortune 500 list)
CareerBuilder
Chicago Board of Trade (pending merger with Chicago Mercantile Exchange to form CME Group).
Chicago Board Options Exchange
Chicago Mercantile Exchange
Chicago Stock Exchange
Citadel Investment Group
Classified Ventures
Click Commerce
CNA Financial (an affiliate of Loews Corporation)
Diamond Management & Technology Consultants
Encyclopædia Britannica, Inc.
Equity Office Properties Trust
Exelon (ranked #134 on the 2010 Fortune 500 list)
GATX Corporation
General Growth Properties
Global Hyatt
Hartmarx
Hostway
Integrys Energy Group
InterCall
Jones Lang LaSalle
Kerasotes Theatres
Koval Distillery
La Petite Academy
Magnetar Capital
Merisant
Metal Management
Midway Games
MillerCoors
Morningstar, Inc.
Morton Salt
National Stock Exchange
NAVTEQ
Northern Trust
Old Republic International
Orbitz
Playboy Enterprises
PTI Securities & Futures
Quaker Oats Company, a unit of PepsiCo
RR Donnelley (Ranked #362 on the Fortune 500)
Ryerson, Inc.
ShoreBank
Skidmore, Owings and Merrill
Smurfit-Stone Container (Ranked #255 on the Fortune 500)
SSA Global Technologies
SymphonyIRI Group
Telephone and Data Systems Incorporated
Tootsie Roll Industries
TransUnion
Tribune Company (Ranked #323 on the Fortune 500)
True Value
UBid
United Airlines (Corporate Offices) (Fortune 500)
Unitrin Inc (S&P 400 MidCap, S&P 1500 Super Comp)
U.S. Cellular
USG Corporation (Ranked #458 on the Fortune 500)
Whittman-Hart
Wilson Sporting Goods
World Book Encyclopedia
Wm. Wrigley Jr. Company
Chicago's Metropolitan Area (outside of city limits):
AAR Corporation (Wood Dale, Illinois)
Abbott Laboratories (Abbott Park, Illinois) (Fortune 500)
ACCO Brands (Lincolnshire, Illinois)
Ace Hardware (Oak Brook, Illinois)
ACNielsen (Schaumburg, Illinois)
Alberto-Culver (Melrose Park, Illinois)
Allstate (Northbrook, Illinois) (Fortune 500)
Andrew Corporation (Westchester, Illinois)
Anixter International (Glenview, Illinois)
Aquascape, Inc. (St. Charles, Illinois)
Arthur J. Gallagher & Co. (Itasca, Illinois)
Baxter International (Deerfield, Illinois) (Fortune 500)
BFG Technologies (Lake Forest, Illinois)
Blistex, Incorporated (Oak Brook, Illinois)
Brunswick Corporation (Lake Forest, Illinois) (Fortune 500)
Calamos Holdings LLC (Naperville, Illinois)
Career Education Corporation (Hoffman Estates, Illinois)
CDW (Vernon Hills, Illinois) (Ranked #376 on the Fortune 500)
CF Industries (Deerfield, Illinois)
Claire's (Hoffman Estates, Illinois)
Corn Products International (Westchester, Illinois)
Così (Deerfield, Illinois)
Coskata, Inc. (Warrenville, Illinois)
Crate and Barrel (Northbrook, Illinois)
Culligan (Rosemont, Illinois)
DeVry University (Oakbrook Terrace, Illinois)
Discover Financial Services (Riverwoods, Illinois)
Donlen Corporation (Northbrook, Illinois)
Eby-Brown (Naperville, Illinois)
Electro-Motive Diesel (McCook, Illinois)
Fellowes, Inc. (Itasca, Illinois)
First Alert (BRK Brands) (Aurora, Illinois)
Follett Corporation (River Grove, Illinois)
Fortune Brands (Jim Beam, Courvoisier, Titleist and many others) (Deerfield, Illinois) (Fortune 500)
Grant Thornton LLP (Oakbrook Terrace, Illinois)
Griffith Laboratories (Alsip, Illinois)
Hendrickson International (Lemont, Illinois; a subsidiary of The Boler Company (Itasca, Illinois))
Hewitt Associates (Lincolnshire, Illinois) (Fortune 500)
Hospira (Lake Forest, Illinois)
IDEX Corporation (Northbrook, Illinois)
Illinois Tool Works (Glenview, Illinois) (Fortune 500)
Kraft Foods (Northfield, Illinois)
McDonald's Corporation (Oak Brook, Illinois) (Fortune 500)
Mead Johnson Nutrition (Glenview, Illinois)
Molex (Lisle, Illinois)
Motorola (Schaumburg, Illinois) (Fortune 500)
Nalco Holding Company (Naperville, Illinois)
Namco Cybertainment (Bensenville, Illinois; a subsidiary of Japan-based Namco)
Navistar International (Warrenville, Illinois) (Fortune 500)
Nicor (Naperville, Illinois) (S&P 500)
NiSource (Merrillville, Indiana) (Fortune 500)
Northfield Laboratories (Evanston, Illinois)
OfficeMax (Naperville, Illinois)
Pactiv (Lake Forest, Illinois)
The Pampered Chef (Addison, Illinois)
Portillo's Restaurants (Oakbrook Terrace, Illinois)
Quill Corporation (Lincolnshire, Illinois)
Rand McNally (Skokie, Illinois), a subsidiary of Quebecor World
Redbox Automated Retail, LLC (Oakbrook Terrace, Illinois)
Sanford (Oak Brook, Illinois; a division of Newell Rubbermaid)
Sara Lee Corporation (Downers Grove, Illinois) (Fortune 500)
Sauer-Danfoss (Lincolnshire, Illinois)
Sears Holdings Corporation (Hoffman Estates, Illinois) (Fortune 500)
Serta (Hoffman Estates, Illinois)
Shure (Niles, Illinois)
SIRVA (Westmont, Illinois)
Solo Cup Company (Highland Park, Illinois)
Stepan Company (Northfield, Illinois)
TAP Pharmaceuticals (Lake Forest, Illinois)
Tellabs (Naperville, Illinois)
The Chicago area, a center of global transportation, serves as the headquarters for airline manufacturer Boeing, commercial airline United Airlines, and a number of major trucking companies.
Tenneco (Lake Forest, IL) (Fortune 500)
Topco Associates, LLC (Skokie, Illinois)
Turtle Wax (Willowbrook, Illinois)
Ulta (Bolingbrook, Illinois)
Underwriters Laboratories (Northbrook, Illinois)
United Airlines (Base of Operations) (Elk Grove Township) (Fortune 500)
United Stationers (Deerfield, Illinois) (Fortune 500)
U.S. Foodservice (Rosemont, Illinois)
U.S. Robotics (Schaumburg, Illinois)
Van Kampen Investments (Oakbrook Terrace, Illinois)
Vanee Foods (Berkeley, Illinois)
Velsicol Chemical Corporation (Rosemont, Illinois)
Walgreens (Deerfield, Illinois) (Fortune 500)
Weber-Stephen Products Co. (Palatine, Illinois)
Westell (Aurora, Illinois)
WMS Gaming (Waukegan, Illinois)
World Dryer (Berkeley, Illinois; a subsidiary of Carrier Commercial Refrigeration)
W. W. Grainger (Lake Forest, Illinois) (Fortune 500)
Zebra Technologies (Vernon Hills, Illinois)
Zenith Electronics (Lincolnshire, Illinois; a subsidiary of South Korea-based LG Electronics)
Companies that have large presence in Chicago Metropolitan Area:
ABN AMRO (Asset Management)
Accenture (Chicago; Global headquarters: Dublin, Ireland)
Acxiom (Downers Grove, Illinois)
Affiliated Computer Services (ACS) (Schaumburg, Illinois) (Fortune 500)
AkzoNobel (Polymer Chemicals Unit)
ALDI (U.S. headquarters: Batavia, Illinois)
Amada Co (Amada Machine Tools America) (Schaumburg, Illinois)
Astellas Pharma (Deerfield, Illinois)
AT&T
Bank of America
Bank of Montreal (Harris Bankcorp, BMO Capital Markets)
BMW of North America (Central Region Office) (Schaumburg, Illinois)
BP (Warrenville and Naperville, Illinois; Whiting, Indiana)
Canon USA (Itasca, Illinois)
Caterpillar Inc. (Montgomery, Illinois)
Citgo (Lemont Refinery, Lemont, Illinois)
ConAgra Foods (Downers Grove, Illinois)
Continental Automotive Systems (Temic) (Deer Park, Illinois)
CSX Transportation (Northern Region Operations Center) (Calumet City, Illinois)
FANUC (Hoffman Estates, Illinois)
Fitch Group
Ford Motor Company (Chicago Assembly, Chicago Heights Stamping)
Fujifilm (Fujifilm Medical) Hanover Park, Illinois)
General Electric
Goldman Sachs
HSBC Finance, a subsidiary of HSBC (Mettawa, Illinois)
Hyundai Motor Company (Aurora, Illinois)
IBM
Ineos/Innovene (Chicago and Naperville, Illinois; Whiting, Indiana)
JPMorgan Chase (See: Bank One Corporation)
Lucent Technologies
McKesson Corporation (Wheeling, Illinois)
McGraw-Hill (Chicago Loop)
Microsoft (Chicago Loop; Downers Grove, Illinois; Northlake, Illinois (data center))
Mintel
Mitsubishi Electric (Mitsubishi Electric Automation, Inc.) (Vernon Hills, Illinois)
Mittal Steel Company (U.S. headquarters: Chicago Loop; plants in Riverdale, Illinois, East Chicago, Indiana, and Burns Harbor, Indiana)
Mitutoyo (Aurora, Illinois)
Mori Seiki (U.S. headquarters: Rolling Meadows, Illinois)
Navigon (Navigon Inc., Chicago)
NEC (NEC Display Solutions) (Itasca, Illinois)
Nissan Motors (Aurora, Illinois (Nissan North America); Marengo, Illinois (Nissan Forklift))
Noritake (Arlington Heights, Illinois)
Nortel (Schaumburg, Illinois)
Northrop Grumman Electronic Systems (Rolling Meadows, Illinois)
OMRON (Schaumburg, Bannockburn, St. Charles)
Panasonic Corporation (Panasonic Factory Solutions Company of America) (Buffalo Grove, Illinois)
Pearson Education, publishing as Scott Foresman (Glenview, Illinois)
PepsiAmericas (corporate offices) (Schaumburg, Illinois)
Popular, Inc. (Banco Popular North America) (Rosemont, Illinois)
Rexam
Robert Bosch Corp. (Broadview, Illinois (automotive aftermarket); Mount Prospect, Illinois (production tools); Hoffman Estates, Illinois (Bosch Rexroth))
Rockwell Automation (Burr Ridge, Illinois)
SAP AG (Downers Grove, Illinois)
Schneider Electric (Palatine, Illinois)
Siemens Healthcare Diagnostics (U.S. headquarters: Deerfield, Illinois)
Siemens Medical Solutions (Hoffman Estates, Illinois)
SSAB North America (Lisle, Illinois)
STMicroelectronics (Schaumburg, Illinois)
Sumitomo Corporation of America (Rosemont, Illinois)
Takeda Pharmaceutical Company (U.S. headquarters: Deerfield, Illinois)
Toshiba America (Arlington Heights; Buffalo Grove; Chicago Loop; Rolling Meadows)
Toyota Motor Sales, U.S.A., Inc. (Aurora and Naperville, Illinois)
UBS AG
Unilever (Home & Personal Care North America) (Chicago)
UPS (CACH) (Hodgkins, Illinois)
UOP LLC, a subsidiary of Honeywell (Des Plaines, Illinois)
U.S. Steel (Gary Works) (Gary, Indiana)
XL Capital (Chicago Loop, Schaumburg, Illinois)
Yaskawa Electric Corporation (Waukegan, Illinois)
ZF Friedrichshafen (Vernon Hills, Illinois)
Zurich Financial Services (Schaumburg, Illinois)