Well, I'm still figuring out this blog editor, so I don't know. We'll see how it goes.
Here are some links to good sites providing textures to use in opensim. I think these are all open source textures, so enjoy:
Second life textures would be the place to start. You'll all recognize some of these.
archibase.net would keep anyone busy for days. This site has many useful textures, some in zip format. Look to the end of the pages for these.
Openfootage.net appears to be mostly one guy wandering around Eastern Europe taking incredible photos and turning them into textures and other content.
Nvidia provides a huge collection of textures, maps, bumps, masks, and such. I use Photoshop and had to download this plug-in to view and edit the .dds files.
If these few links don't keep you busy for days, then I can't help you any more. Go away. They have been a great source of textures for me and a great sucker of my time, particularly when the grid is down!