Heikki Lehvaslaiho has created a script for interactively querying the Internet Movie Database (IMDB) for movies and then creating a Bookcase data file. It's great, I've already been playing with it quite a bit. It even supports downloading the movie images, along with alternative titles, global certifications, etc.
Heikki did a great job commenting the code, too. You might need a couple more perl modules, but that's straightforward enough. urpmi to the rescue, for me.
All of you who have been emailing me about this functionality, well, go grab imdbfetch.pl and go at it. You can append the resulting data file to your current collection so you don't lose any of the data you've already entered.