Creating seamless textures: tessellation (tiling) in GIMP
Sometimes the best way to find the exact texture you want for a build will be to create your own. A photographic texture of a real brick wall, for example, is likely not only to enhance the feel of authenticity of a structure but also to add a stamp of uniqueness to your build. (And, of course, authenticity is all the more important when creating an in-world model of a real-world building, such as we did in 2007 when replicating in Second Life the Tower of London.)
The problem with using photographs, as taken, is that when tiled the edges are more than likely to mismatch (see example, right). Fortunately GIMP has a plug-in that will convert a raw image into a seamlessly tiling background. Open your photograph in GIMP and, from the Filters menu, select Map and then Make Seamless.