Gmote is a smart remote application for your android handset. It lets you search through the folders of your pc and start music or videos. You can control the mousepointer using the touchpad functionality.
Install the app from the android market and start the server on your system of choice: http://www.gmote.org/server
For whatever reason, I had to enter my pc’s IP manually. On Ubuntu, you can find out your IP using ifconfig.
More information: http://www.gmote.org/