I was never much one for sending lots of texts, but I know I'm very much in a minority on that score. If you do spend a lot of money on SMS messages, Vodafone's latest offer may appeal. Vodafone's offering the Infinite TXT plans in three flavours; $39 straight on either a 12 or 24 month plan scores you $300 of plan "value" (always a slightly rubbery term) for standard and international calls and MMS and 500MB of data with a choice of smartphones; the example given is the Galaxy S II. Bump that to $79 and you'll get $750 of "value", 1.5GB of data and an HTC One X. Finally, for the bring your own phone SIM-only crowd, a $30 plan with $300 of value and 500MB of data.
All three plans have as the central hook infinite text messages both nationally and internationally, and come with Vodafone's Network Guarantee, which essentially means if they don't work in the first 30 days, Vodafone promises it'll make it easy to back out of the contract, paying only for the bits you've actually been able to use. [Vodafone]