Ravi Kabob in Ballston stays open late (either 2 or 3am). I am a huge fan of Ravi Kabob, but I've never been late at night. I am not sure if the menu is limited during off-peak hours. Their bone-in chicken kabob is great! And those spicy chick peas are heaven.
Oh Kabob Palace in Crystal city (which is similar to Ravi Kabob) is also very good and open either super late or 24 hrs. Mehran in Foggy Bottom is also in the same vein as Kabob Palace and Ravi but no where near as good, IMHO. Also open super late.