http://www.linux-wlan.org/docs/wlan_adapters.html.gz
Now there's a list. Unfortunately it just tells you chipsets, and 1/2 that list you couldn't find anymore with E-Bay and a bloodhound.
USB + Linux + Wireless = a life of hell.
At least the last time I was really back in the hardware game, bout January-ish, sorry, been on a bit of a vacation :-)
Anyway, a PCI card will be easier to the point of comical. I think you can even yum or apt-get or whatever you package manager of choice is, the given driver for your card when you get one. Or, if you're feeling hefty, just compile the driver.
I'm a big fan of the Atheros line of chipsets, basically any card on that list that says "Atheros" will work with:
http://madwifi.sourceforge.net/
For most of the others, if you want to just blind buy, there is always:
http://ndiswrapper.sourceforge.net/
Actually, you may want to give ndiswrapper a shot right now with the USB one, don't know what the mileage will be like, but 802.11g even over USB 2.0 is somewhat of a speed slap.
Cheers,
Finegan