Gnome Phone Manager
I just discovered this useful application by searching for a way to send SMS messages from my laptop.
I already had a mobile phone that could send messages, and this little app will integrate with your cell phone via Bluetooth so you can send messages from PC to phone (so the phone can send the message) and when you get an SMS message on your phone, it will pop up on your PC.
I thought this was a great addition to my already busy desktop, but I have found it to be a handy tool when you don't have to remember where you put the phone just to send an IM to someone. As long as the phone is within Bluetooth range and you have the application started, you can send and receive SMS messages and do it all from your desktop.
It's in the repos.
Here's the web site to tell you more.
sudo apt-get install gnome-phone-manager
If at first you don't succeed - just buy the company and tell them to make the one you want.