I do sometimes. Usually just go through the work I'd done that day, organise my folder, read my english text, stuff like that. Nothing too heavy. I'm less than 20 away from my station, so I'm not given that much time. :\ Plus, there are usually people talking and it's really distracting.
(Train-- if it was bus I'd get sick doing work, though reading is fine) Sometimes I just look out the window, or observe others.
Or pass out for a few mintes...