Maybe a battery charger/starter, jumper cables
Also I like to keep a few quarts of oil, tranny fluid, oil and fuel filters, prop puller spare prop, grease for trailer wheel bearings etc...
When you need that stuff, it's nice to have it right there, and not have to run around town to pick it up.
Oh and beers in the fridge!
...cleaning and working on a boat is kind of like BBQing for me, hard to do without a beer in one hand
(Message edited by rio_sanger on July 11, 2009)