Does anyone know an way / or an app to change the default ringtone for a certain contact so when you receive a text, it doesn't beep?

I want to set Twitter up to receive through text messages, but don't want to hear the text sound every 5 minutes.

Before anyone suggests it, i've had a look at the twitter clients but don't really like any of them.

Thanks
Bryan

If the text messages (SMS) are coming from a specific phone number you can use message blocker - the thread is here - This application will also block instant messages from yahoo and skype.