I mentioned not long ago about the use of digital noise for creating textured backgrounds in WPF applications. While noise can be appealing, it is just one of the many kinds of textures you can use in your application. While some can be created programmatically like our noise was many are created from scratch using image editing tools, or from photos or scans of real-life objects.
Atle Mo has created a nice site for sharing pattern textures, called (appropriately enough) subtlepatterns.com. The hard thing (for me) about creating these kinds of things from scratch is making them tile well, and the contributors to the site have saved us all the effort. The site allows you to preview the patterns as backgrounds for the site itself, they are all licensed under the very permissive Creative Commons 3.0 Unported license which allows both commercial and free use of the patterns. It is well worth checking out. And just in case you’re thinking textures and patterns have no place in modern metro design have a look at this screen shot of the zune player for some inspiration.