Since I live smack in the middle of Dupont Circle, I'm biased :-)
1. Wrapworks (Corner of Connecticut and Q)
2. Chipotle (Connecticut btwn Q and R)
Weather permitting, grab your burritos from the above locations and find a place to sit in Dupont Circle. Great people watching location!
3. Raku (reasonably priced Asian at 19th and Q - spring rolls here are quite good)
4. The Diner (On 18th but in Adams Morgan - great place for a cheap brunch)
5. Peppers (On 17th btwn P and Q somewhere - fabulous pretzel crusted chicken entree)
6. City Lights of China (on Connecticut between R and S - arguably the best Chinese in DC - be sure to get the steamed veggie dumplings)
7. Penang (19th and M - great ambiance and curries)