Last week I happened upon 7-week old Cafe Gelato, on St. Elmo in Bethesda. After two visits, I recommend you try it.
They have a wide variety of gelato flavors (chocolate hazelnut, canteloupe, pistachio, strawberry, espresso, plus about 20 more). The ones I've tried (and they do let you sample) are flavorful and fresh.
I was told by the guy at the counter that all the gelato is made in-house, and that the flavors are more vibrant than most ice cream because (surprisingly) there is less fat in the gelato.
They have sandwiches and salads, too, but I haven't yet tried them.
P.S. They are open late--'til 10:30 most weeknights and later on the weekends.