TestFreaks posted a how-to about creating seamless textures with Photoshop CS4

This how-to will show you two of the most popular methods for taking a regular image and making it seamless using Photoshop CS4; one of the industry's most popular image editing tools. With the right steps, a little know-how and a splash of artistic ability, anyone can learn to take any image and remove the edges for a nice, natural tile.

How-To: Creating Seamless Textures with Photoshop CS4