I was shopping around for a bit looking for a really good car mount for my Captivate. After a bit of research I came up with the iGrip 1263 Extender Kit. I've taken a picture of the barcode for you all.
This is by far the most stable and nicely made universal mount I have found for a reasonable price. On the box it says its designed for trucks and the like, but it isn't too big that it looks ridiculous in my Hyundai.
It holds the phone pretty damn securely, whether in portrait or landscape, and it has a telescoping arm that can make it come closer to you. (while this makes texting and driving with Swype very easy, I don't recommend it.
). I got this thing on Amazon for $29, and I think it's worth it. Also to be noted, the way this holds the Captivate doesn't block ANY of the side buttons. I'd recommend checking this thing out if any of you were looking into a car mount.