I have a Sony Ericsson T610 mobile with Bluetooth. I don't really use the Bluetooth for much as the Bluetooth handsfree I tried was useless (echo and poor sound quality), but when looking for software to backup contacts from the phone I found something very interesting. float's Mobile agent:
FMA is a powerful phone editing tool allowing users to easily manage all of the personal data stored in their phones, via a number of different connections methods. FMA allows easy management of Phonebook (both SIM and Phone memory), SMS, Profiles, and Files stored on the phone. FMA can also allow you to pickup and dial calls directly from your PC.
It has all the normal features you would expect from this type of software, but there is one additional feature which stands out. You can use VB-script which will be displayed as a menu on the phone! And when you choose an item in the menu a function in the VBScript is executed! That means you can control your computer using your phone! How great isn't it to relax in bed and just click 'iTunes -> Next song' or 'Shutdown computer'. Great use at a party if you have your computer hooked up to your stereo. Don't want the laptop full of beer now do we?
Check it out: