Perform

Performance art is a tricky thing: the more you talk about it, the less it seems obvious. I've already mentioned that the internet is not the place to look for resources in this domain. You can always try. Just don't do it for too long, or you will end up thinking that it's either something horribly idiotic, so abstract it's completely devoid of meaning, simply and completely mad (the latter site has some excellent cases though!), or plain dead. (I made the selection based on Google's top choices).
Fortunately, the ancient wisdom of printed paper comes to the rescue. Besides the brilliant book I've been recommending for a while called Live:Art and Performance, there is a new, exciting book out called simply Art Works Perform.
Why is it exciting? Because its aim is to show how very different things performance art can be. It is full of short... well, I would call them adventure stories (although some last a lifetime). Like the one about Andreas Slonimski and his stealing a bicycle pump in the most unusual of ways (artistic, of course), or about Olafur Eliasson's rivers of color, or about Rirkrit Tiravanija's challenge of engaging the audience in the most positive of ways.
What is also wonderful about these stories, is that they really show different people, in different worlds and working in different ways. Some dance, others take pictures, or write, or make pizzas, garage sales, lines of yellow paint or of pigeons, or make water fall. They all share one thing: an outstanding sensitivity, which makes this book a collection of powerful, inspiring moments. The book also has several "extras", works curated for the publication and interviews, but I must admit I'm much more overwhelmed by the combination of original artists (though the interviews are good, too).
There were 2 other things I really liked about the book: first, it is signed by Joan Jonas, an artist I really admire. And second, it's really cheap. (At least at Amazon it is).