Here are a few websites that offer Photoshop tutorials that demonstrate various techniques you can use in your digital scrapbook layouts.
Digital Scrapbook Place - Digital Scrapbook University
ScrapbookBytes.com - Tips on using Photoshop
Pslover.com - Random Photoshop Tutorials
Using Brushes
Giving a page artistic flair
COMING SOON....
Creating a curve
Making your own template
Digital stitches
Making a scalloped frame
Digital glitter
Using digital layout templates