What would you want to ask a prospective employer anonymously?

I'm working on a service where you can find the answers to all sorts of questions about a company before going through an application/interview process to work there. The questions will be asked anonymously, so you don't have to worry about a poor impression negatively affecting your chances of getting the job.

Especially for you developers out there, what kind of thing would you want to know that often isn't written in the job description?