Pondering post-apocalyptic science fiction as a game setting. Whether I should put the work in, whether I should go for something fairly straightforward or totally oddball. Either way could work, and I've never really done either. Outlaws really wasn't properly post-apocalyptic.
If I go serious I'll want to get d20 Future. Very cool book, I once borrowed it from a friend. If I go with something fantasy/bizarre, I'll have enough material that I won't feel a strong need to go out and buy it. Probably. Chaositech has rules for mutants, I can hack together rules for robots, and I hear BESM d20 has a pretty nifty set of SRD rules for mecha.
I'd really like to put together a feat-tree type system for mutations. Actually, I could just use feats for that--maybe with a class that grants bonus mutation feats. Hrm. That would take work, but it might be worth it.
If I was going to run a post-apocalyptic game.