Duke Nukem Forever has been in development for a long time -- so long that it's hard to keep tabs on everyone who's touched the game. As a result, Gearbox is giving past contributors a chance to be in the credits.
The DNF Credits site welcomes anyone to submit their name. Be warned that Gearbox will be verifying the information to make sure "I.P. Freely" isn't credited as a past developer. The entries that pass Gearbox's verification will be named in what is sure to be the longest credits sequence ever.
So if you've worked on Duke Nukem Forever at any point during its 10+ years in development, make sure you get your name in. If not, the form has a "Fan" option for Mr. Freely.