I've been playing with making a 3D model of the piste data I collected at Isola 2000 ski resort. Taking the GPS tracks that include elevation data and combining them with the ways that I plotted into OSM I've written a little application that will render the resort as a 3D image that can be rotated, zoomed etc. Still a work-in-progress and unlikely to every be generally released, but I'm having fun making it.