The Flat is one of my favorite "fast food" spots, and---really---the food is awesome (they're also able to be super accommodating to both gluten free and dairy free dietary restrictions). The only problems I've run into is that 1) there's nowhere to really sit if it's busy, and 2) they seem to be always closed! Maybe it's gotten better recently, but right off the bat, they're closed Sunday and Monday. If there's inclement weather or something comes up, they just shut their doors. Definitely check this place out, but be sure to have a back-up plan.
This place is pretty no-frills, but they've got the best breakfast in Charlottesville, period. Regardless of what you're into: vegetarian, vegan, gluten-free, bacon aficionado, they can handle it. My favorite dish is definitely their corned beef hash, but there are too many good ones to pick from. For my fellow bacon lovers, make sure you snag a side of "pig candy." :)
For us dairy-free folks, you simply cannot beat their sorbet (especially if you like chocolate). For those more lactose-inclined, Splendora's has some of the most authentic gelato that I've ever seen. This is a definite Cville staple.