I'm using a Verizon MiFi 2200 I purchased separately and using the 1GB/mo prepaid plan for $50. I know it isn't the best value $ wise but there's no contract and I can shut it off for a cycle here and there if I really don't need it.
I've tested Verizon service all over the country and it is remarkable how good the coverage is. I've yet to not be able to get online anywhere I've been, including some very remote areas. Speed varies but overall it is as fast as a basic DSL connection but mobile and I can hook up all my devices anywhere, anytime. It's fantastic.