Post your favourite textures in this thread.
There are texture creation programmes on the net. Here is a selection
MapZone: Free, quite complex to get to grips with but very powerful. (as at 2009)
Genetica: $150 for the basic version, but there is a free viewer you can download with some very nice presets. (as at 2009)
Texture maker: 30 day free evaluation, great interface costs 30 euros for the basic version. (as at 2009)
Filter Forge: Basic $149, Standard $249, Professional $399, Professional by subscription $29 per quarter. (as at July 2014)