I got the "Charging Holder with Tilt Swivel and Cigarette Lighter Adapter" through yesterday.

I'm very impressed with the holder - the N900 fits in very well and is held securely, with the USB connection fitting perfectly. You can open and close the screen while it's in the holder as well.

I'm far less impressed with their mounting mechanism though - using 4 screws to connect the holder to the mount. Why not have some sort of a clip? That way the holder can be easily removed when not in use (or you could move the holder between cars, boats, planes, wherever you're wanting to use it). In addition to that, one of the mount clips broke while I was trying to fit it, so I'm now going to have to chase up a replacement