Hey, this is kind of out-there, but I'd suggest some sort of bloopers track during the credits of all the voice actors saying random stuff in-character, or sending in their funnier fail-moments from recording lines, if they haven't deleted them already. Or maybe simply record the same lines but with outrageously caricatured versions of themselves, like when Simon Pegg and Nick Frost redid a Hot Fuzz scene as Sean Connery and Michael Caine.
I was just rummaging through the FS2 wav files and found Commander Snipes' "Bite Me" and "Stop laughing pilot!" lines, and it gave me the idea.