If you aren't already, please consider collecting their tenure with the company. That way, you can see who's been there a week, a month, a year, or ten. Then, once you've been running this for a while, start looking at the data for patterns. See if people get unhappy after a certain length of time. Or, see if the responses all take a downturn after a certain date.

Then see if you can correlate that with public output from the company: products, services, that sort of thing. You could have something really valuable here: a finger on the pulse of a bunch of companies, in effect.