Damn Cool Algorithms, Part 1: BK-Trees
Some implementations:Lisp: http://cliki.net/bk-treePython: http://hupp.org/adam/weblog/?p=103Ruby: https://github.com/threedaymonk/bktreeHaskell: http://www.robdickerson.net/?p=346Java: http://code.google.com/p/java-bk-tree/