The compensation part is actually really interesting. My particular industry is notorious for using really strongly worded non-competes. Those don't fly at all in California but they do fly in a fair number of other states. In Illinois there was a court ruling that stated that non-compete agreements are not enforceable unless a specific bonus is paid for signing the agreement. Continued employment (in that case of just under 2 years, after an acquisition) was not enough compensation.

So, if you are asked to sign one of these things either ask for some cash up front or hold in your back pocket that it's probably not enforceable (though it can certainly end in litigation which can be terrible for everyone involved).