Kanoozee - Free SMS dating tell others and make cash
Clickatell – Download there software and get 5 free sms credits.
1rstwap - Send free sms to mobile phone users anywhere in the world. Lengthy registration is required, but (I think) it's worth it - very fast sms!
BoltBlue - You can send SMS text messages from your PC to almost any mobile in the world. Register with Boltblue to receive 15 free text messages per month.
ICQ - "Use ICQ to send mobile messages to your friends' & family's cell phones whether they have ICQ or not!" Need to have an ICQ number (requires installation of ICQ software).
Procomsoft FREE SMS - Send free sms text messages to a variety of countries (personal use only). Registration is required to use this service, however - businesses only, it seems (your business needs to be a member of a specific online business directory - and an activation code is sent to your email address.
Send Free SMS Worldwide - Send Free SMS Worldwide, no registration required