Recommendation systems can be very valuable but they also tend to direct you to the most popular things. "This is popular" is not the same as "you’ll like it". Finding ways around that might prove to be even more valuable for users of these systems.
"An easy way to mitigate this is to selectively decapitate the recommendation engine’s results. Last year I blogged about Andrew Grumet’s “Similar Feeds”, which implements this. I just came across a music filtering site that makes the feature more prominent and intuitive by putting a nice, fat “popularity slider” right at the top of recommendations pages. Try playing with the slider on this page to see how it works."