I'm interested in electrical vehicles, and decided to build an electric bike. I purchased a kit from china with a hub motor and mounted it on my bike. Biking is so much more fun now!
I put the battery together from cheap lipos from HobbyKing, and built myself a AVR based charger. The batery is charged with constant current until its voltage approaches 4.15V/cell, then the charging is aborted. The electronic fits nicely in an empty ice cream container, and a little forced air convection keeps it cool enough.