Bracketron. Best Buy sells them in different versions. Mine has the suction cup, (bought it for my Vision M), which works great with the Droid off the windshield. Horizontally or vertically. Takes very little time to plug in charger and transmitter(Pandora!). Should be easy to mount a magnet but I just launch car/home manually.Not sure if this will help you, but thought I'd pass it along.
I just purchased the dock shown below, except that the one I purchased comes with double sided tape, a vent mount, and screws to attach to a separately sold mount from the same company.
I'm using the vent mount, which is easy to put on and take off. But...
my point is, this is a very elegantly designed dock! You simply put the Droid (or gps or whatever) against the back of the dock (which is nicely padded), then squeeze the two side arms together, and they hold the Droid in place.
The two side arms are composed of two pieces, which can be squeezed together, or moved apart to give a wider area holding the device when installed. They can also be raised or lowered independently of each other. The two side arms are also nicely padded.
The bottom legs pivot.
What's great about this design is, 1st, you can install the Droid with or without a form fitting case! Once I purchase my seidio inno case, which will add slightly to the overall size of the Droid, this dock will still work perfectly!
Also, being the side arms move up and down, you can move each side out of the way of plugs and/or switches... I can lower the left side to expose the usb port when I want to charge the Droid in the dock, while raising the right side, so that it doesn't accidently hit the camera button!
Not sure if you can contact the company that makes these, and perhaps purchase only the dock, not any of the mounts (cup holder, vent, cig lighter) and customize those with a plug?
There are a LOT of things that you need to consider when designing a dock, esp. if you want it to work universally, for different items ( I realize you only need it to work for the Droid, just saying....)
This company has done an excellent job!
(The Droid is securely held, even though there's nothing holding it in place in front of, or overlaying the droid. It's only held in place by being squeezed by the two side arms, but it is very secure!)
Hope this might help you!
Good luck!