When I ski and snowboard I listen to my iPod nano -- usually just choose the genre (hip hop) and let it shuffle. I wrote a script to intelligently randomize to go from 40GB PC to 4GB nano. Slacker G1 doesn't work so well from a pocket, although I snowboarded to
rosco|radio once and it was very appropriate.
For the car, Slacker G1. I use it via a first gen Harman/Kardon Drive+Play -- it's an iPod accessory. Bummer the Auto Aux Input function they have doesn't work.
I also have a Nokia 770 (a Linux internet tablet). Hackers have figured out how to use up to I think 16GB memory cards now, so it can function kinda like an iPod but I use it for other things. Speaking of Linux I've also run Linux on my nano for awhile. Somebody will eventually hack the Slacker into a dual-boot Linux device, no doubt.