Right now I'm really enjoying H2o wireless, it's very cheap, and $10 USD lasts you 90 days. They apparently use the AT&T network, so the coverage is just as good as AT&T at least. Domestic and International calls are only $0.05 each, and Domestic text messages are $0.05 as well. If anyone has found something better I'd love to hear it. I don't use my mobile that much, Google Voice handles most of my business phone communications and I'm at my computer most of the time during the work day.
Boast Mobile offers unlimited talk, text, and web for only $35 a month on smart phone plans. I would say that is definitely better. $.05 a text adds up quick.
Hmm. $35 a month. I spend $10 and it lasts me 3 months. I think I've still got the better plan. If I ever start using my phone more I'll check out Boost though, thanks for mentioning it!