A lot of recommenders begin and end their lives as part of corporate research tools, with the possibility that the tool will end up being marketed to clients. One of my favorites was the LikeMinds system which was tested through a website called Movie Critic (tm). Movie Critic had a simple and fast interface, and it was also used, from what I remember, on Cinemax's website. LikeMinds ended up in the hands of Macromedia, and I suspect that it has been integrated into some larger products. It is no longer a highly visible product, but one outfit, calling itself MovieCentral, built itself from the Movie Critic system (and even allowed users to import their old ratings). And then folded.
Movie Critic generated preconfigured recommendation lists, as well as a prediction for almost any movie (along with a confidence score). With those predictions, it would also tell you where your prediction stood in relation to users average ratings (i.e., you will like this better than most people). Finally, the one really cool thing that Movie Critic did before it shut down was that it let you do a sanity check. This is useful when there is a large range of possible scores to give an item. In this case, what Movie Critic would do is generate a list of 13 movies, one for each possible score, and you could then correct as necessary.
I also liked the cute Ward Sutton cartoon at the top of the page.