How to acquire or generate test data for a recommender system

Question

I'm currently researching recommender systems and would like to know how other researchers acquire or generate test data to evaluate the systems' performance?

Answer 1

When I was working with Recommender Systems I had the exact same problem. I enjoyed the Grouplens dataset the most:

http://grouplens.org/node/12

You can download ratings given by users to movies.

Also, I described in my blog some datasets I found while researching:

http://girlincomputerscience.blogspot.com.br/2010/12/datasets.html

Hope it helps!