What's the best prepaid cell phone plan for just texting?

Hey, my girlfriend's parents refuse to let her add texting to their plan, and as you probably know, single user plans are prohibitively expensive in the extreme. What would be the best prepaid plan such that she could just send text messages? I'm patial to the ATT network, but I could do others if necessary.

virgin mobile has a plan called texters delight. it runs $19.99 a month for unlimited texting and if you use voice minutes they are .10 cents per minutes. check coverage at virginmobileusa.com it runs on sprints pcs network so texting is reliable. hope that helps