I was fortunate enough to be able to spend some time today learning yet more incredible things about Adobe Photoshop.  (I'm using version CS3.)  For anyone wanting to expand their techniques in PS, there is, IMHO, no better resource than the National Association of Photoshop Professionals.  A one-year membership is $99, which is a bargain.  Their monthly magazine, Photoshop User, is incredible.  I have at least portions of every issue I've received over the past 4 or 5 years; they are that helpful.  Their website is also full of video tutorials, tips, downloadable actions and brushes, book and product reviews, and on and on.  Members also get a substantial discount on many resources, including books, videos, and software.  Those discounts alone can pay for the cost of a membership.  I've seen Photoshop User on the newstand at large bookstores, so you could pick up a copy there if you want to check it out.

As a photographer, Photoshop is my modern darkroom.  I hardly ever shoot a picture, either professionally or personally, that doesn't go through Photoshop.  Sometimes they just get cropped or tweaked.  Other times they get morphed into something totally different from the original image.  At any rate, everyone who shoots should, I think, consider Photoshop the necessary post-shooting step for every photo.

I actually spend more time in Photoshop than behind the camera these days.  I am more than happy to share my always-growing knowledge of PS, so if you have a question about a technique, feel free to ask.  If I don't know the answer, I can probaby at least direct you to the right place to find it.  And when I can't figure out how to do something, I'll throw my question out there to see if anyone else can help me.