On demo at CES was Unify4Life's Slide|Shadow, which allows you to use your BlackBerry to control powerpoint presentations! Here's the official verbage:

Slide|Shadow: we took our technology from the Game|Shadow and created our first entry into the enterprise market. Plug Slide|Shadow into your PC (Windows 98+, MAC, Linux) and your smartphone can control PowerPoint slides, in addition to acting as a keyboard for the user's PC (which has many industrial applications). It seems our engineering team watches a lot of downloaded video's, running from their PC's; so they use it as a remote for Windows Media Player! No software or drivers on the PC are required, just a simple download onto your BlackBerry. Slide|Shadow will be available April 2009 with an MSRP of $39.99. 

Be sure to watch the video above to see Slide|Shadow in action!