Great idea! And also for text spammers (another complete annoyance) there's a great app (free) called HandCent that allows you to block certain cell numbers, or even block any texts from an unknown number not in your contact list. If that makes you nervous that you'll miss someone important texting you, you can set a custom ringtone alert for non-contact texts :)
I am watching my language, that's why I can't really say what I think of these !@#$%^&;-)
Particularly, since the GOV's DO NOT CALL LIST IS TOTALLY INCOMPETENT WITH ENFORCEMENT!!!!