Anderson Powerpole connectors are my connector of choice for the bike. They are small (about 1"x.5" x.25" for two contacts), rated up to 45 amps, modular, genderless, color-coded, and have self-wiping contacts. Lots of different modular parts are available, like panel mounts, cable housings, strain reliefs, keying elements, and the like. They are vastly superior to any Radio Shack connector that I have used and are the defacto standard in the HAM and emergency communication field.
There are two parts to each connector: a metal contact lug and a plastic housing. The contacts can be crimped on to the wire or soldered, and the housings snap onto the lug. The housings are square and lock together in any configuration you want. The 15A contacts accept 16AWG to 20 AWG wire, the 30 A contacts take 12AWG to 16AWG wire, and the 45A contacts are new and I don't have the info on them yet.
The BMW plugs are robust, electrically, but the housings are fragile. I've broken several by dropping the end of the jacket cable on the ground, or by accidentally dragging them on the ground. At $9 each, that gets old fast. While the housings on the Powerpoles can crack, they are cheap (less than a dollar for a complete set) and easy to replace. Mostly, though, they are light enough that they won't crack just from their own weight falling on the ground.
With a set of adapters I can connect almost anything:
Caution: since they are genderless, you could possibly create a dead short by plugging a positive to a negative, if you put the wrong color housings on, put the mating connectors together the wrong way, AND connected two supply leads together.
The full line can be seen on the web at Anderson Power Products and click on "Powerpole" but that site was terribly slow last I checked. A cheaper and better source is Power-Werx and there are many other great goodies there also.