This is probably a good thing:
German teacher loses court battle against rate-your-teacher website
I can understand both sides here, but I believe that a low ranking from a biased student who failed the course would be offset from a biased student who aced the course. Eventually - given a large enough number of reviewers - a true evaluation of that teacher will come out.
I can remember even as early as grade 6 having a teacher who loaded on the homework, was very strict, and even though all students despised him/her, most were quick to agree that he/she was a great teacher. Students recognize when a teacher is passionate about their job and when they care about pushing students to their potentials.
Anyways, I bring this case up as I feel that Online education (especially those attempting to market a product) should embrace rating systems as well, either through their own LMS or through third party sites. While most departments of eLearning products will create surveys for their own internal feedback, they should instead strive to create a recognized quality learning experience that is rated publicly by their users. The current and new generations expect to see user ratings, and when a learning product has a five star rating with "76 learners rated this product" it will have a stronger affect on their decision then having a stock photograph with a quote from 'Billy'...not that there's anything wrong with that.
Don't be afraid to show what users think of your products. Earn some gold stars. Plus user ranking is so web 2.0!