^ I use the speck transparent case -- I'm on my second one.
If you drop your macbook while inside your bag a lot .. the case tends to break lol.
But .... both times my case broke my macbook was completely unscathed, so replacing a $50 case didn't hurt that much
Btw, if you do get the speck I recommend it because they leave a small gap in between the case and the macbook pro itself, so if a small piece of dirt/debris gets in, it can't chafe and scratch the hell out of your unibody.
/OCD
Another option is the Moshi Iglaze -- I've been thinking about buying it if I break my current case (which I probably will...)
http://www.moshimonde.com/product/ig...e-black-1.aspx