Photoshop
Absolute Cross - Lots of tutorials, downloads, and neat tools to make web design easier.
Adobe Photoshop - Can't forget Adobe's site for tutorials on their own product!
Designs by Mark -- A definite Photoshop guru! There's a lot to learn on this site.
Developing Webs.net - This site has some very nice tutorials, especially for glass effects.
Eyeball Design - A good number of tutorials with some interfaces available for download.
Eyeland Studio - Some free tutorials and interfaces, plus a CD with more matieral for sale.
GifArt.com - tutorials from Photoshop 4 through 6, plus clip art.
GUIStuff.com - Free interfaces and tutorials for Photoshop, Flash, and more.
HeatheRowe.com - Great Photoshop tutorials and I love the understated, classy site design.
Ice House Designs - Some Photoshop 6 tutorials, plus some design tips and useful scripts.
Photoshop Gurus - Lots of tutorials for different levels of ability.
PS Workshop - A database of Photoshop tutorials across the web.
Web Class.ru - A very large selection of Photoshop tutorials to browse through.