There's a very cool new app available on Mobihand... MobiMouse - Turn Your BlackBerry Into A Mouse! - Personal Productivity Blackberry Software
If you have a use for it, as I do, it'll become indispensable. Even if you don't have a real need for it, it's still pretty cool to play with.
Mobimouse allows you to use your BB to control your mouse cursor, type from your BB keypad, and manage volume up/down/mute on any Windows computer - you can connect your BB via WiFi (if your BB is WiFi enabled) Bluetooth (all BBs have Bluetooth), or USB cable. Once connected, Mobimouse turns your BB into a keyboard and mouse for your computer. Ditch stuffing that mouse in your bag the next time you hit the road for a business trip!
The trackball controls the mouse cursor (press the trackball to "click" just like on the BB), you type w/the keyboard keys, and the BB up/down volume & mute keys control the sound. Right-click is the BB escape key, so you can even get to context menus.
I have a PC attached to my TV at home that I use for watching Netflix "Watch Now" movies/shows, playing iTunes MP3s off my home network, and some internet browsing. I used this app to connect my BB to my PC via BT and manage all my mouse/keyboard/volume activities on the PC via my BB. Even my always technology-blasť wife is impressed. :D
They offer a week free trial, and it looks like the app is reduced to $7.99 until the end of the month. Check it out.