Here's a simple idea that might help:
http://www.marginalrevolution.com/marginalrevolution/2004 /11/paying_for_perf.html
Why not... as the article says, a lot of parents do that so let's have a portion of the salaries that would go to administrators of failing districts redirected to students who pass tests.
I can see it now. Those teachers who really hate the administrators will make sure all of their students pass the tests... even if they have to write the answers on the chalkboard.
It could work if the tests are administered in SAT or ACT fashion, but it might get out of hand if the "student mafia" gave the teacher "an offer he couldn't refuse".