SIM only, voice + data, GSM, no contract? (Score 1)

I'll be visiting the U.S. soon for 6 weeks or so, and want a cheap(?) connection with national roaming (no phone needed) along the lines listed above.

Both Cingular's and ATT's (old) websites are un-navigable when looking for something this specialized, in my book.

Any recomendations of deals from /.-ers?