computer science

http://williamedwardscoder.tumblr.com/post/87682811573/compressing-scrabble-dictionaries Efficient ways to store Scrabble wordlists.

http://cs.nyu.edu/~fergus/research/deblur.html This paper is magic! It covers a method to remove motion blur from images.

http://www.lel.ed.ac.uk/~gpullum/loopsnoop.html A poetic proof of the undecidability of the halting problem.

http://mitpress.mit.edu/sicp/full-text/book/book.html The book Structure and Interpretation of Computer Programs by Gerald Sussman and Hal Abelson is available for free online. This was the introductory computer science textbook at MIT for several decades.

http://cg.scs.carleton.ca/~morin/misc/sortalg/ Java applets which visually demonstrate various sorting algorithms.
http://evan-roth.com/9to5paintings.php These are graphs which show a user's clicks throughout the day as a single image.