Burrows-Wheeler transforms

I think that the BWT (Burrows-Wheeler transform), and particularly its inverse, are one of the coolest things I've ever seen. It's easy enough to see how someone could have thought of the forward transform, but the reverse transform is one of the most counter-intuitive ideas I've ever seen.

Go take a look: http://en.wikipedia.org/wiki/Burrows-Wheeler_transform

(As a sad aside, I was in the CL on the day that David Wheeler died -- I regret never having got to know him. I'm told by an old friend (ex-PhD student) of his that we'd have got on) 

Edit: The original paper is here, but is much less readable than the Wikipedia article.