eZeText

From the developer: "With eZeText, you have a more efficient but also a very much cheaper way of keeping in touch with your collegues and friends. Getting the messages and information to its destination can average as little as a penny for each SMS message, direct from the big, beautiful keyboard of your computer to any mobile phone.

"Via a computer and modem or directly via the Internet, you can have a messaging system which allows you to group 'address lists' of numbers for your teams as well as last minute reserves and also all your frequently dialled numbers. eZeText works across all the mobile networks and logs messages. There's even a built in dictionary.

Requirements:

Windows 95/98/Me/NT/2000/XP