I have a friend who works for a small, but reasonably profitable, organisation (they're agricultural traders, so they make a lot of money). He's been there for years, and he really doesn't like the long hours and general stress of it. But the boss likes him so much, every time he says he's thinking about leaving, or his boss finds out he's interviewed somewhere, he gets a raise.
Got Wal*Mart to do that for me. I was the only "senior" employee and the only one that knew how to fix the machines in the photo lab. Course a percentage of nothing is still nothing. Glad I don't work there anymore.