The Innosilicon A6 can do 1.23Gh/s
http://www.innosilicon.com/html/a6-miner/index.htmlBut, minimum order quantity is 50 and I personally feel it's overpriced based on current revenue potential. But, you asked what is available that can do more than a Gigahash, and this is the only device I'm aware of. Also keep in mind it's really nothing more than two A4+ paired together on a single controller so maybe that's cheating to say it's a "single device" that can do more than a gighash :-)