Driving around usually, but could even be walking or biking, with a laptop, or some sort of electronic device that connect to a hotspot (wireless internet access point, or node) - and usually just using the node to browse the internet or whatever, and usually mapping its location.
*Cough* POCKETPC *cough* Not some damn *cough* Palm.
Ive got one, I watch Divx videos on, beautiful screen quality. Can fit 2 full length MOVIES on 1 512meg SD card. Can fit 5 if I reduce the size and bitrate accordingly.