I am not sure what you are looking for exactly, but I know that Historic Landmarks offers a bunch of different tours all around Indianapolis and Central Indiana that I have heard are pretty good. I work downtown and see people on these tours quite often (if that counts for anything). Their most notable I believe is the Landmarks on Foot walking tours that are offered May through October. You can get more info on all of these at: http://www.historiclandmarks.org/things/heritage.html (broken link)
There is the Haunted Irvington Walking Tour and the Irvington Tour of Homes. I know that Meridian Kessler has a home tour as well.
If you are into the paranormal (or just want something different to do), some have mentioned that the various historic indiana ghost and walking tours (
http://www.unseenpress.com) have assorted Indianapolis Ghost Tours that are pretty good. And the Nefarious Noblesville tour is said to be great too.
There are always individual tours of the many landmarks and sites around the city like the President Benjiman Harris home and the James Whitcome Riley house, Scottish Rite, Sailors and Soldiers Monument, the Monument Memorial Mall and the Indianapolis Motor Speedway.
Easley winery has their tour as well
http://www.easleywine.com.
Something that I do every year is the Eastside Pub Crawl. It's so much fun and it takes you to a sampling of the great (I use that word loosely) Eastside establishments. It sounds strange but it really is a good time if you bring some friends. Here is a link to last year's event, but I don't know when the next one is yet. It's usually every spring and fall. You can contact the person on this link I suppose:
http://www.woodruffplace.com/news/000112.html (broken link)
I hope that this helps!