I, too, love my 17" PB. The biggest downside is the lack of availability of a great input device for the road. I use a Kensigton Expert Mouse Pro trackball with my desktop machine, and really love it--11 buttons plus chording, scroll wheel, excellent software, and no tangled mouse tails.
I put a Logitech cordless optical mouse on my wife's machine. It works well, but I much prefer a trackball. So for the PB, I would like to have a trackball, but the Expert Pro is way too big to haul around. Since the PB has built-in bluetooth, I'd love to have a great little Kensington-type bluetooth trackball. I spoke with one of the Kensington guys at MacWorld Expo-SF, and though he wouldn't say anything about a trackball, he did say they would be coming out with bluetooth devices "this spring".
I have also seen a handheld device with a small thumb-operated trackball, though it was corded, PC only, and pretty of cheesy construction.
Dave Jochum
J o c h u m A R C H I T E C T S http://www.jochumarchitects.comMBP 16" (M1 Max) 64 GB•OS 15.3•AC 28 Silicon (latest build)