If you can show the existing OSM map on your GPS* while tracking and taking photos, you can check where the map is fairly complete and where it is worth taking extra pictures/notes.

To show the map on a GPS there are several solutions. I have (good) experiences with both a Garmin GPS unit with a converted planet file[1] and Motion-X GPS on the iPhone. The latter works with a live connection, but also allows you to download tiles beforehand.

For photos you may want to check if you can find a camera that records the location with the photo. Some relatively inexpensive cameras (in phones) offer this functionality. This would save you stitching together photos and track.

For notes I’m afraid I’ve yet to discover the perfect solution. If you come across something that allows you to mark a spot, add a remark and save it with a minimum of hassle I would like to hear about it.

Regards, J-----.

[1] http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin