I try to avoid national chains and the usual glut of greasy, crappy fast food stuff, but there are a lot of local food carts and quick stop places that are really tasty. Off-hand, I'd say Perierra Crêperie for late night noms, Sizzle Pie and Tugboat Brewing Company for quick food and beer, and maybe Chipotle if I'm stuck in the suburbs.
Tons and tons* of brewpubs around town that serve cheap, locally-grown, goodies and beer, and can have you in and out in 15 minutes, too. I have a standing habit of hitting a pub for something quick before digging around used bins or going to shows.
* The Portland-Metro area has like 300 microbreweries, most of whom have a restaurant or 12 somewhere in town. It is awesome.