SMSTray

"With SMSTray, you'll be automatically notified of received text messages directly on your desktop, and be able to easily reply or send new text messages without touching your phone.
SMSTray features full address book integration, sent message notification, and is simple to setup and use. SMSTray takes full advantage of Bluetooth connectivity with your phone to provide a seamless text message environment."
Nice for someone that is tired of typing on the phone and wants to send and receive sms directly from the computer. Not my king of app. I love my phone too much to miss an occasion of typing something on it.
It's made by WildPalm and it costs 9.9E. You need Windows XP Service Pack 2 to use this you can buy it from WildPalm