Skip Lists: A Probabilistic Alternative to Balanced Trees[PDF]. Saw a link to the original skip list paper. I'm not sure whether I've read that one or not. Anyway, if you want to understand concurrency, and the "impending multicore future", skip lists are an interesting thing to consider. Note, the rest of this post assumes a basic understanding of ( Read more... )

Via Simon Willison: Found in Space identifies what part of the night sky your flickr photo is looking at. Which is pretty darn cool.

Even better, they have a link to a paper describing the scale and rotation invariant hashing algorithm[PDF] they used.