I have the problem (and social stigma) of flying for my job and for a hobby.
Flying for job:
1. Map - Has most of the info you need on it. If not you can write on it.
2. Chinagraph (for writing on map).
3. Watch - Russian wind up so no batteries to run out. To be used in conjunction with compass (usually already fitted to aircraft).
4. Wallet - Contains ID card, credit card and a bit of cash.
Flying for fun:
As above + Licence.