MORSE

MORSE first ran on the World Wide Web in 1995. It was one of the earliest collaborative filtering systems and, as far as I know, the first to be applied to movie recommendation. Its accuracy was only surpassed about twelve years later, by a Netflix Prize entry.

Paper published on MORSE.
Dead On Time. MORSE's algorithm applied to missing data.
MORSE on Wayback Machine. (The CGI script wasn't archived, so it won't run.)