Tutorial: Create the OS X 'Aqua' look in Photoshop
Sarah Green writes "I Heart New York: X Icons, offers a handy tutorial on how to use Photoshop to create that Aqua look that appeals to so many Macintosh OS X users. They've also got a bunch of free Pop-Culture icons for download: Andy Warhol, Bewitched, Gumby, Tintin, Radiohead etc. Worth a look."
Also check out http://www.pixeljerk.com/.
They have a Photoshop action for creating Aqua buttons.