Hoof, I didn't know about the alt-clicking between layers. I do the same thing, but I use Ctrl-G while on the top layer -- it automatically "groups" with the layer beneath it. Bone, if you want something a little more precise than the magic wand when selecting a not-so-pure color, you might want to try Select > Color Range. I also sometimes use the path tool, and more lately, I use a plug-in called KnockOut 2.0 by Corel (I won it in a contest, and it's been super, super useful in nearly all of my compositing work).