I have a SERO mobile broadband plan that no longer is available that has served me great. The plan is "unlimited" although i think it is now softlimited to 5gb just like all the other carriers. The monthly bill is $49.99 instead of the $59.99 that is currently being charged. The plan is valid until May 2010 so you can easily save $180 in data from now till then.

I'll sell the plan along with the Novatel Ovation U727 along with original boxes and accessories for $90 shipped. The card works great on both my macbook air and thinkpad and along with the SERO plan it is definately the cheapest/legit mobile broadband plan available right now.