If you have a blackberry you know how good their excellent messenger service is. Its free from BB to BB as it uses your data allowance to send the message. The down side was thats its only Blackberry to Blackberry, but now the new Whats App messenger application from those very nice people at whats app enables users to send sms messages or photos free of charge from iPhones , Blackberry , some Nokias ( all the new ones ) and android..

Its free so go check it out..