After reading Cameron Moll’s suggestion of the Logitech Cordless Presenter for presentations I ordered one from Amazon. Fortunately it showed up in time for me to use it at WordCamp Denver last Saturday (kudos to Alex, Devin on putting that together!) so I was able to use it in front of a real audience. It worked great, no problems at all plugging it into my MacBook Pro and flipping slides in Keynote. The laser pointer came in handy for presenting on a large screens.
It’s more expensive than I would like, but it’s worked great so far.