Throwback uniforms, or pretty much any cool or unique uniforms, have always been a favorite of mine. That interest has begun to manifest itself in a subcollection of cards. I'm devoting an entire section of my binder to baseball cards that have pictures of players in throwback/awesome uniforms. So far, I only have about a front side of a page full, but I'm hoping to make some trades with 20youksox and maybe find some dime-box pickups along the way.
Also, I've been inspired by Dime Box Nick over at baseballdimebox.blogspot.com to start valuing cards (that can even be as cheap as a dime) for more than their book value: whether it be cool photography, nostalgia, or any other things that set apart these "gems" (as he calls them), I'm going to try to pick some up whenever I see a dime box. I'll even try to devote a section of my binder to dime-box pickups.
Needless to say, I'm hoping to advance my collection of cool uniform cards in the near future. You all should really check out Dime Box. It's linked on the sidebar blogroll on the right hand side of your screen. Soon, I'll have scans of how my collection is progressing.