I keep hearing of fuel cell technology being "right around the corner", but had yet to see real production units. Voller Energy seems to actually be producing something that is usable and which you might actually be able to buy when it launches commercially in 2008. Designed to run from LPG, propane or butane, they are already aiming for the marine and RV markets, among others.
This might be a technology that fits well with my timeframe, although costs will be of course interesting.
They recently had one of their pre-production units on a yacht that crossed the Atlantic (it was sail, but they were using the fuel cell for electric power, as I understand it).