I bought one of the Schumaker onboard battery chargers, and modified it slightly.
(sounds like a line from Home Improvement..)
I cut the black and red charger cables at about half their length, and attached insulated wire connectors to the exposed wires. I attached only the terminal leads with the six or so remaining inches of cable to the battery terminals,and when not in use, I leave the charger in the garage. To connect the charger, I just "temporarily" plug the wire connectors together.
The advantage of this setup is that it avoids the need to drill any holes in the car to attach the charger, and it avoids a bit of unnecessary weight. Really little or no extra effort to hook up the charger beyond what would be needed if it were permanently installed in the car.
[This message has been edited by westernb4 (edited 28 January 2002).]