In my Photoshop Masking seminar last week I showed how to mask difficult subjects such as hair, fur and feathers. Doing this successfully requires you to evaluate your image and choose the best tool/approach for that particular image. One useful tool for certain masking situations is the Filter > Extract command, which is in Photoshop CS2 and CS3, but was removed from CS4.
However, you can still use this command. Just download the "Photoshop CS4 Optional Plug-ins" (Mac link) (Windows link). Install the "ExtractPlus" plug-in, and the Extract command will appear in the Filter menu in Photoshop CS4.
Greg wrote to me after the seminar and pointed out the "Photoshop legacy optional plug-Ins" (Mac link). Download this, and install the Macintosh only "Overscroll always" plug-in. This plug-in lets you scroll over to reveal the gray backdrop around your image, even if your image is larger than your active window. Normally, you can't scroll past the edge of the image, but sometimes you need to in order to make a quick selection with the polygon lasso or Pen tool, for example. Thanks Greg!