I wrote a small rails app for this for a small community bank. We had 150k users, each user "belonged" to a branch and we had a 50 man (women really) call staf

I wrote a small rails app for this for a small community bank. We had 150k users, each user "belonged" to a branch and we had a 50 man (women really) call staff. The branches were different in location, size and age so each had a different amount of customers assigned to it. So we setup a list of x number of answered surveys per branch. Big Old branch needed 40, new small branch needed 10. Call center rep logs into the system. It randomly picks a customer. They call, if the survey is answered, they mark it otherwise they click next and get a new customer to call. We allowed for comments, and a checkbox for "would like to be called back". As the surveys get answered, a branch got "full" and its customers stopped showing up. Once all branches were "full" they call center reps were done for the month. Next month, the branches were all reset, and we started again, but not picking any customer we had already surveyed (or had asked not to be called, or was in the do not call list which we updated monthly). We reset a customer so we could call on them again after 6 months had passed since their last survey. The branch managers were given the "bad ones" and the ones that requested a call back to work out any issues. Their score affected their bonuses, so it was taken seriously.