Damn Cool Algorithms, Part 1: BK-Trees
Some implementations:<p>Lisp: <a href="http://cliki.net/bk-tree" rel="nofollow">http://cliki.net/bk-tree</a><p>Python: <a href="http://hupp.org/adam/weblog/?p=103" rel="nofollow">http://hupp.org/adam/weblog/?p=103</a><p>Ruby: <a href="https://github.com/threedaymonk/bktree" rel="nofollow">https://github.com/threedaymonk/bktree</a><p>Haskell: <a href="http://www.robdickerson.net/?p=346" rel="nofollow">http://www.robdickerson.net/?p=346</a><p>Java: <a href="http://code.google.com/p/java-bk-tree/" rel="nofollow">http://code.google.com/p/java-bk-tree/</a>