One of my favorite blogs, Six Revisions, has a list of 25 Photoshop tutorial made specially for web designers. Enjoy.

Photoshop Paper Texture from Scratch

How to Create a Grunge Web Design

Create a Sleek, High-End Web Design from Scratch

Design an Awesome Band Website Template

Designing a CSS based template (Part II, Part III)

Create a Dark Themed Web Design from Scratch

Design Watercolor Effect Menu

Volkswagen Inspired Navigation

Glossy-Style Carbon Fibre Navigation Buttons

CSS Menu With Icons

Content Box with Orange Banner Heading

Modern Web Search Bar

Professional Dark Header

Pro Header With Picture and Navigation

Hero Header Part I

Header Backgrounds

Design a Unique Header

Design Studio Header

Professional Header Design

Create a Latest Tweets Box

Light Tabbed Content Box

Create a Dark Content Box with Glowing Navigation

Greenish & fresh content box design

Designing a Unique Bookmark Box

Creating a Grungy Banner

Source: Six Revisions