You've Got Spam - A new tool that lets you spam back the spammer
Clockwork SMS - Clockwork is an Easy Text Message API. An SMS API for Developers. Build powerful apps and include SMS. Signup is free, Try it now.
Clean SMS - Filters out spam SMS on your Android phone
Twilio - Brings voice and messaging to your web and mobile applications.
Callwarden - Go to war on spam calls 📵
Crypton.sh - SMS - Secure Anonymous SMS in the cloud (and a phone number)