Cex.io is also offering BTC for USD with their latest interface you can check the site
http://cex.ioMore difficult than anticipated. May require same full address, ID, verification methods as Bitstamp per use.
Im presently attempting the mobile verifications...albeit they're fraught with poor instructions
if you stay below a certain limit there is no verification, usually this limit is around 500-1k, it should work for cex too, otherwise look at bitfinex