Got this for $5.50 shipped on eBay, quite satisfied! The ball is the same size that is used on our stock Droid car mounts. It uses tough 3M adhesive and is all around good quality. Eliminates a lot of the play and bulk found with the stock arm. Great for getting the Droid out of the direct sunlight on the dash as well.
I picked one of these up as well. I liked how it has a little more "reach" and would work better if the base was attached to a horizontal surface:
Received the two mounts. I ended up using the one posted in the OP (first image) because it is more compact and suited my needs better for the space I mounted my wife's Eris. However, I thought I would mention that the base "plate" is rather thin and there is some flex in both the plate and the short/thin arm on this mount. I can't believe this mount would be good at supporting the heavier Motorola Droid. Though I admit I haven't tried the mount with my Droid.
The other mount, pictured in the second image is much sturdier/rigid. And it has a much wider base, but it IS quite a bit bigger in all dimensions. If you have an area large enough on your dash or instrument panel to put this big boy, then IMO, it would be better for the heavier Droid.