I can get TAP for $40 a month without Text plan.
Actually, there is an iPhone app out there to address this! It’s called Textfree, from Pinger.
Textfree Unlimited provides unlimited texting. You can get it through this link on your iPhone:
http://www.google.com/url?sa=t&source=web&ct=res&cd=2&url=http%3A%2F%2Fi tunes.apple.com%2FWebObjects%2FMZStore.woa%2Fwa%2F viewSoftware%3Fid%3D305925151%26mt%3D8&ei=tQI_Suai O4HCtwey1KEU&usg=AFQjCNETib8g8-GcJkqo4uaud5K31BBT7g&sig2=esB4x65JjfUmyoZNBAVlXg
There is also a free version of the app (Textfree Lite):
http://www.google.com/url?sa=t&sourc...04xRAGbiNE8xDA
The only thing left lacking is tethering and MMS.