Door Arm Rest?

Anybody try to put an arm rest on the door by the bottom of the window? I had one on my last car but it was cheap and I had to literally screw it into the door to keep it in place. I want something similar because I spend a lot of time in the car and it makes it much more comfortable, but don't want to have to ruin the door panel to do it.

Here's something similar that I found online:

http://www.jcwhitney.com/arm-restler-universal-arm-rest/p2023697.jcwx#

Has anyone tried putting something like this on their 2?

Well, I tried it out and I have to say, it is very comfortable. However, you have to cut off some of the part that slides between the window and the gasket because you can slide it down very far. It stayed for about half my commute today before falling off, I think because I put too much pressure on the edge closest to me, so it slid out because there's not much holding it in place.

I'm going to see if there's a way I can get it to stick a little better, but it seems that, as long as I rest my elbow on it completely, rather than just the edge, it should stay fairly easily. The good news is that it's easy to put on and take off.