how about foreign language lessons, if your mobile phone data plan (for skype) or call plan is good enough to make it worth it, and you have excellent coverage

how about foreign language lessons, if your mobile phone data plan (for skype) or call plan is good enough to make it worth it, and you have excellent coverage along your whole route. That likely pays more than most other things you could be doing, however it will require a lot of attention. Is your driving pretty monotonous?