The day is drawing closer to when you will be able to throw off the shackles of the all mighty dollar and throw on the shackles of the all mighty hat. Today Steam Market has entered open beta! What this means to you is that you may now start selling virtual game goods for Steam wallet funds. Right now it is only applicable to TF2, and only to consumable items (keys, crates, MvM tickets, paints, etc) but will surely open up to more items and games as it progresses. http://www.teamfortress.com/post.php?id=9567
FTFY Apparently they charge a 15% fee on top of a fee determined by the game publisher (see "TF2 Fee" in FAQ). Not sure if want... I forsee massive exploitation by shifty individuals, and tanked key prices as people buy keys with idled metal to sell them below store cost for hard cash. Might be smart to get your keys into refined ASAP.
It's more or less an alt to the Mann Co store at this point, most people are undercutting valve by quite a bit.