Hi Lendrick,
This kind of stuff is very useful for making textures, thanks. I've already got them all downloaded and saved into my reference folder. I'm not a license guru, but generally we prefer stuff released under GPL 2 or later. Would it be alright with you if I released derivatives in that license?
Also, I noticed that they're all saved in JPEG format. One of the things JPEG does to save space is combine like pixels into blocks. This is fine when viewing it as a photo, but one of the most common things that I do with reference photos is use a color selection to extract bits of grunge and other texture details, which I can then paste over an existing photo to give it some detail.
With some JPEG photos, the blocks prevent me from being able to do this. You can see what happens in the example screenshot I'm attaching here. It's really only a problem in textures that have chunks of similar-colored pixels like the one in the screenshot. The file /Ground/2010-09-04_08-10-28.jpg doesn't really have any problem because there's lots of strongly contrasting detail.
You don't need to go resaving all of them, but might be something to think about for the future. Saving in PNG makes the files much larger, but there's no loss.
edit: I split the topic so we can discuss your photos separately.
edit again: I forgot to attach the screenshot