Refer to this link, it's updated as new mobile GPUs come out:
http://www.notebookcheck.net/Mobile-Gra ... 844.0.html
If you refer to the 3dmark06 column for each GPU, you can sort by score to rank them. It's got pretty much every mobile GPU that you can imagine.
Since we've established in Guard's thread that video cards should be your first deciding factor, this is a great site for comparing laptop GPUs.
Do keep in mind that these 3dmark06 scores are done with a certain configuration--that is, with a certain CPU, usually dual core, and a certain speed, type, and amount of RAM. Those factors can be quite drastic in determining the score you will get, so do pay close attention to the CPU that each of the laptops comes with.
edit: gay, how do I make this a sticky or announcement