Good question. Roster bonuses, and that's about it, right?
I know first-hand that one player -- Chris Cooley -- makes and sells pottery and other artsy things at a new gallery he bought in December. Went there Friday night for a showing. While it's nothing near what he makes in the NFL, he's doing OK based on the prices of some of those things. Dude also went to his local Redskins team store -- where he gets 40% off -- and bought up $6,000 worth of his own jerseys. He signed them and has them for sale at his gallery for $275. All kinds of other signed memorabilia there, too. Hats, shirts, pictures, framed jerseys, etc...
I overheard him telling someone that he's been pretty smart with his money and that he's doing just fine during the lockout so far. Apparently, some are not.