Jerusalem Felafel, on the west side of Broadway and I think between 104th and 105th Sts., has pretty tasty felafel.
Another place that hasn't been mentioned yet is El Malecon, called "El Rey de Pollo" ("The Chicken King") for its great Pollo a la Brasa (rotisserie chicken). It's on Amsterdam between 97th and 98th Sts.
For classic diner breakfast fare, the Broadway Restaurant on B'way and 102 is the best in the neighborhood, IMHO. The egg/bacon/grits platter is very satisfying, and the food of surprisingly high quality for the relatively low prices (e.g.only real butter used) The service is friendly, and the place is REAL, unlike the overpriced, prettified Metro Diner down the street.
For a quick/cheap dinner on the go, the Supertaco truck on Broadway and 96th Street is great. They are only there after 6 p.m. on weekdays; earlier on weekends.
Flor de Mayo on B'way and 101 has delicious Peruvian chicken, with satisfying sides like black beans, yellow rice, and maduros (sweet fried plaintains.)
Indus Valley on B'way and 99th has best Indian in the neighborhood.
Pampa, Argentinian Steak place on Amsterdam and 98th, is especially nice in good weather when you can outdoor eating in the garden in back. (Cash only, however.)
You def. have to stop by Absolute Bagel, as someone already mentioned.
Cafe Con Leche - Amsterdam and 96ish
Turkuaz - B'way and 100th
Crepes on Columbus - Columbus and 105ish
And I know it's not the best slice, but you gotta try Koronet (B'way and 110th) for the novelty alone.
The pickings are slim right up here, but a couple of things you might try - Silver Moon Bakery on 105 & Broadway, they have a few tables outside if the weather is good and their croissant and french bread are excellent, and they have interesting sandwiches at lunch time; also for breakfast, Picnic on 102 & Broadway, serving Silver Moon bread, omelettes etc...pricey, but good. The Cafe du Solei is to be avoided at all costs for all meals, bland, overpriced food and sub par service, even for the UWS. Classic UWS breakfast, good if you are up and out early, is Barney Greengrass, the Sturgeon King at Amsterdam between 86 & 87. Fab food - try the nova and scrambled (won't have to eat again for a week or so!)
http://www.chowhound.com/topics/400183 is a great thread full of UWS rec's.
You'll be very close to Absolute Bagels, which has great chewy salty bagels. If you feel like walking for 15 minutes over to Harlem, you'll hit Zoma (113th and Frederick Douglass/8th Ave) my favorite Ethiopian, and Lee Lee's, home of fabulous "rugelach by a brother"