Cupcake Cafe on 18th Street: I've been to the one on Ninth Avenue several times. I thought the cupcakes were overpriced and not very good; part of the reason is that they were so cold that they tasted stale. I think the best cupcakes are at Amy's Bread (
Amy's Bread | www.amysbread.com | Welcome) The full pieces of cake are even better.
S'MAC (mac 'n' cheese place) on E 12th Street: They make great mac 'n' cheese but it is, ultimately, mac 'n' cheese. It's also very, very rich. It makes me want to take a nap after eating it.
A few other cool, only-in-New-York places:
ChikaLicious Dessert Bar at 203 E. 10th Street (
ChikaLicious Home Page) An all-dessert restaurant. It's tiny (about 15 seats) and there's almost always a line (but it moves quickly and is certainly worth the wait).
Kyotofu at 705 Ninth Avenue (
Kyotofu) Another all-dessert restaurant. All of the deserts are Japanese inspired and many contain tofu (but they're all delicious).
Shake Shack in Madison Square Park (
SHAKE SHACK) A burger shack in the middle of one of the most charming parks in the city (in the shadow of the Flatiron Building). It's just a burger, but made by one of the most respected chefs in town (Danny Meyer). There's usually a long line.
Momofuku Noodle Bar at 171 First Avenue (
:: momofuku :: (http://www.momofuku.com/noodle/default.asp - broken link)) Get the ramen with shredded pork; I think it's only $9.00 or so. Chef David Chang charges $300.00 (with wine) for lunch at his other restaurant, Momofuku Ko. Your get the same attention to detail at the Noodle Bar at a fraction of the price.
Bouchon Bakery in the Time Warner Building at Columbus Circle (
Bouchon Bakery | Home) This is Thomas Keller's bakery. He's one of the top chefs in the world and the mastermind behind Per Se (generally regarded as the best restaurant in New York). It's very hard to get a table at Per Se (and it's also stupendously expensive) but anyone can walk up and get something delicious at the bakery. Grab a snack to go and then walk across the street to Central Park and enjoy.