One of the best places in DC for a quick lunch is a small restaurant called Breadline, which features a little indoor seating, a little outdoor seating, and very good bread. It is very popular and usually has a long line at lunch time, but people move through very quickly--the people who work there are fast.
The problem is that Breadline has daily specials, and since they are so busy it is tough to get someone to answer the phone when you call around lunch time to ask what those specials are. So if you really feel like the excellent potato and leek soup, you just have to go there and hope for the best.
But the wonders of the internet have made all Breadline lovers' lives much easier! They now have a site on blogspot that provides their daily specials! So now I can check before I leave for lunch and never be disappointed again. If you're in DC and haven't checked them out yet, you really should.