Intellectual property contracts are common in finance. I had a clause that, if enforced, would have prevented me to work for two years in the industry, while offering half my usual salary in the meantime. I think it's fair (doesn't hold you off forever and also doesn't starve you while you're out of the game). In my case, it wasn't enforced when I left (which is more bad news for me than good, since it just means I wasn't valuable enough :)