I run a tail box most of the time (Seahorse case on a Caribou rack and mount), so I keep my Aerostich tire repair kit, rain pants, an extra pair of gloves, allen-key tool, various chargers for my electronics (iPhone, Sena, etc) and some extra tie-down straps in there all the time. I like the idea of all the bike's and farkles' service manuals on a thumb drive; I might have to do that and keep it under the seat.