Current top favorite is:
http://www.gbmcllc.comReally low prices on many things. Ammo, guns and tons more. Plus they offer free membership (near wholesale pricing) for military (former, retired & active) police and fire/ems. Also you get flat $15 shipping with the code NMGT. Makes those big ammo purchases reasonable. Also nice that they are smaller. He's got Buffalo Bore handgun ammo in stock and it is about $19 less than what cheaperthandirt.com sells it for. I do like cheaperthandirt.com for their huge selection though.
Since I'm in New Mexico, I like
http://www.newmexicoguntrader.netInteresting stuff pops up on there. Guy just sold a whole SKS package for $600. Multiple mags etc. Can find a good deal on there and I don't have to bother with shipping fees and FFL fees.