If you're not looking for a sit-down place, I recommend one of the many trucks on campus.
Don Nemo (sp) burritos, tacos, & tortas - 38th & Sansom
Magic Carpet, Vegetarian fare - 36th & Spruce
Crepe truck on Spruce btw 36th & 37th
Try Lemongrass at 36th & Lancaster. 3 courses for under $10. Service can be a little rushed.