Atlas works for folks in the US as well, but we don't support LLCs yet. You can register an LLC by yourself with the state of Nevada or Wyoming for a trivial amount of money. There exist hundreds of companies which will assist with form preparation (of which LegalZoom is probably best) but both states now have a web app which produces an adequate cookie cutter LLC for software professionals with very simple needs.

Nevada is more convenient and modestly more expensive IIRC; Wyoming is more privacy-conscious. I own 2 Nevada LLCs; as a consequence of this, my address is trivially available on the Internet. If that gives you pause, Wyoming a good option.

I've heard good things about incorporating LLC online with http://www.legalzoom.com/