Downloadable content for Duke Nukem Forever is on the way. And while it's not at all compelling to those who aren't into the game's multiplayer, at least it's free for First Access Club members. (You need to have registered before DNF launched in your country, however.)
The Hail to the Icons Parody Pack adds in a few modes -- Freeze Tag (like the ending of Demolition Man), Hot Potato, and Hail to the King -- plus maps inspired by popular videogames. Those would be Call of Duke, Sandpit, Inferno, and 2Forts1Bridge. I see what you did there, Duke.