All of the professors in the science department at my university would tape lists of their student's IDs and their test grades outside their office through out the semester including finals. When looking for classes for the following semester, I just had to look at which professors gave better grades on average and sign up for their classes. The difference was quites staggering.
Some professors consistently failed roughly half of their students while others would have over 3/4 the class with A's consistently. Granted, there were some variable to consider like which course was being taught and the fact that some groups of students are sometimes simply better performers than others. But there was no way I was going to see that kind of data displayed publicly and not take advantage of it.