Whenever there's a movie I want to see that's not yet released for rental I add a task "Watch MOVIE". When the movie is listed on LoveFilm I add the URL and the rental release date if available. I use a smart list searching for the work "watch" and periodically and/or when I get reminded I review the list and add the movie to my LoveFilm rental list (completing the RTM task) or updating the release date.