Photo Textures: Flypaper Textures

I recently came across the photo textures from Flypaper Textures, and they seem to have attracted a fan base. Used to add "depth and interest" in a picture, applying an overlay texture creates a more painterly effect (appearing as painted with a brush), and sometimes an impressionists like style. Some of the examples from Flypaper Textures are perhaps a bit on the over-saturated end, however will definitely stick in a Flickr stream.

Although the basic principle is simple; overlay an image with less than 100% opacity, some of the tutorials available are interesting: from Flypaper Textures itself, CoffeShop blog, and a video from Digiscrap101.

Finally, here's a similar tutorial in GIMP, focusing on the layers features. His example is a lot less subtle though, but the same principle and functions apply.