smsBlocker is a neat little app that monitors your incoming SMS messages to filter out unwanted spam. The first time you run the app it searches through your existing messages to find those that may be spam. It then shows these messages to you to allow you to decide whether you really do want to block the relevant numbers or not.
By default, all numbers in your address book are marked as allowed so that it doesn’t accidentally block messages from friends. You can also setup words that you want to block, add new numbers to your blacklist and mark other numbers as allowed. There are logs to show you what's been filtered and you can even set a different tone to sound when you receive a message that the app thinks is suspicious.
If you're plagued by spam text messages, smsBlocker will help you eradicate the problem.