Thanks!

Thought about it, have some original concepts I could do that for, but haven't for a few reasons. A lot of the times I'll do an original concept but use things like music or audio I don't have the rights to "sell" for money, like the death theme for Sonic in the recent Road Runner game. I could probably choose a different song in cases like that, but since I'm NOT selling my work I just don't worry about it.

The other reason is to my knowledge you cannot upload a game for free on Steam, so to put games there would be operating at a loss so in the end it just doesn't really make sense for me.

I'm not opposed to collaborating on a game that ends up on Steam as a team effort, so that might happen one day, but so far no one has approached me with any ideas like that.