Window only: Free application Ant Movie Catalog manages your movie collection in a personal database. While not as immediately user friendly as other tools covered here, such as Griffith, Ant offers a thorough database that allows you to catalog not just standard fare such as titles, year of release and so forth but also detailed information about the actual media itself such as codecs, audio format, resolution, and so forth.
Ant Movie Catalog supports plug-ins and an extensive script system. It comes prepackaged with scripts to access over 211 movie databases (compared to Griffith's 22), which range from standard pop culture fare via IMDB to lesser known Anime and foreign films. There is also built in support for 30 languages and the ability to import databases in common formats from other media managers.
Like Griffith, Ant offers a loan manager, but Ant's is easier to use with a more streamlined, single-window system for tracking the DVD you lent to your pal. Unlike Griffith, Ant Movie Catalog is not multi-platform; it's a free download for Windows only. Thanks gottwhat!