GenieTexter is a Free SMS sending program which works for Windows systems only. It runs via a scripting system and there are scripts available for a number of free SMS sites.
An address book allows you to store names and numbers, so you can refer to people by name rather than by their mobile number. You can send a message to multiple recipients and if your message goes over the standard 160 characters it will automatically be split into two text messages.
The site also offers other helpful utilities for organising your texts.
Registration required, etc:
Registration required? Don’t Know
Receive messages? No
Confirmed delivery of messages? No
Message length?
Message Quota? 160 (sms over 160 characters automatically creates a second sms)