I used to work at a place that did this. We had an online system that everyone was required to use twice a year to rank every other employee from best to worst

I used to work at a place that did this. We had an online system that everyone was required to use twice a year to rank every other employee from best to worst. You could also provide comments. When everyone was done they showed you what your results were and how your average ranking compared to everyone else. The results were anonymous (except for one time when a glitch let everyone see what everyone else said about them). The comments were generally not very helpful, but for those used it to give good feedback it was mildly beneficial. Some people took it seriously and gave feedback which was useful. Other people used it to vent and others merely went though and added things like "Good employee" to meet the required number of comments. Most of us hated it, but I think the management liked it. You could instantly see what your employees thought of each other. When it came time for evaluations and raises, the results always closely aligned with the results of your peer rankings. Here's a question to ponder: in general, would you rather your raises be based on your peer's assessment or on your boss's?