Spare strings (Martin or Adamas), lots of picks, jaw harp, fingernail clipper, mini faux Leatherman-tool for clipping strings, capo, New Skin liquid bandage for those times when I've not played in weeks and don't have much for calluses (a mando player I know recommends Super Glue, but y'know, I don't think so), electronic tuner, string winder, those big metal clips for clipping music on a stand, used to have a C-harp until I loaned it, more or less permanently, to a friend, and a small hand towel for wiping down the guitar and such (always know where your Towel is).

Nothing too out of the ordinary, I guess.

Chris