Every once in a while I take my JrF contact mics and go out looking for a good sounding wire fence. I learned this technique while on the Wildeye courses with Jez and Chris Watson a couple of years ago, and I've kept my eye out for this type of fences ever since. Hopefully someday I'll have enough material to put together a library, but until then I find great pleasure in sticking the contact mics to a random fence and listening back while looking like a complete weirdo to passers-by.
Here's a short downloadable and royalty free snippet from a recording of a fence I found today: