Backstory: Yes... I've been on a bit of employee management kick lately. We've been trying to our overall process; creating a positive feedback loop to help retain and improve everyone in the company. Last quarter we tried a random piece of software to facilitate everyone in the company rating each other... we ended up using excel and A LOT of formulas and manual copy paste, no bueno.
The Idea: An anonymous system for employees to rate each other and give feedback.
Deep Dive: You would have to build a platform where employees can log in and see a set of co-workers to rate. There are cases where it doesn't make sense for everyone to rate everyone, a designer may never interact with a PPC marketer.
Taking it a step further than just ratings, you could offer a free-form feedback section. You could also setup a regular schedule to email users to fill out the forms. As this project expands you can offer different tiers and advanced analytics to track which employee is improving.
Validation: We've tried to find a solution and resorted to excel.
Monetization: You could offer it for free for teams < 5 and charge per seat after. This grows with your customer.