http://members.ozemail.com.au/~binaryfx/PSTV_links.html#M This site is my Bible for all things Photoshop. The author of the site is a resident at one of the other forums I visit and is respected for his knowledge.
It may be a little dry going in places and is technical to the nth degree, but it is a collection of informative and authoritative links.
Scroll down to Masking and Extraction for the links you are looking for (however I suspect that all the other techinques will grab your attention too)
Enjoy!
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"When fishes flew and forests walked and fig grew upon thorn
Some moment when the moon was blood, then surely I was born..." G.K. Chesterton - The Donkey

