You've Got Spam - A new tool that lets you spam back the spammer
unscan - Scanning of user-submitted content made simple.
Castle - The easiest way to protect your users from getting hacked
MyHumans - Block calls from numbers not in your contacts
RoboStopper - Block spam calls or get paid for them wasting your time
OOPSpam Anti-Spam API - The better, new standard to stop spam content.