There is no official hotkey to select all layers in Photoshop. You also cannot set one in the Keyboard Shortcuts menu. But it's still possible! Here's a tip on how to select all layers in Photoshop.

Learn how to create real 3D text all inside Photoshop CS5 Extended! This tutorial will show you how to create a grungy poster out of the modern 3D text effect that you will learn how to make. You will also learn some tricks such as how to randomize brush settings to avoid “clone-stamp patterns”.

In this Photoshop tutorial, you'll learn how to create an urban filter in Photoshop. This effect is great for night time city photography. As complex as it looks, this effect is created from only three layers.