As a result, you get recommendations that are musically similar, but often new and unexpected.
The indexing is based exclusively on mood and the ratings are user-contributed. I can forward contacts if someone wants to know more about the project.
I think my gut reaction against it is that people might reject a perfectly good recommendation because they didn't like the reasoning. For example, if we recommend something to Alex because Bob likes it, but Alex doesn't trust Bob's judgement, then Alex might reject the recommendation even if in practice she always enjoys the same things as Bob, she just doesn't realise it.
On the other hand, collecting feedback about whether the user agreed with the way the recommendation is made might be helpful in improving the way it works.
Definitely something to think about though.
We do list LoveFilm - which is Amazon's UK service. We don't list Amazon Instant because we're UK focused at the moment.