I've never really looked for these, or thought about them explicitly, in my contracts. They feel very standard and I feel like I may have overlooked the implications for these in the past.
I have refused to sign contracts with non-competes several times in my life. Most companies either remove it or say, "No there's not a not compete. Oh .. huh .. well I'll remove it." I've had two companies fight me over these and I came close to walking away from both, but we ended up being able to work things out.
Most realize they're not enforceable in most states and I've even seen contracts that specify "except in California" since there are laws restricting non-competes there.
You can always ask for money. If someone asks for a 6 month non-compete, ask for an X month parachute (where X depends on how narrow the field is and how likely it is for you to find a job in a different field). You might have to negotiate something wrt being terminated with cause, or if you terminate the contract.
That can end up being a bit complicated, though. My standard is to only agree to non-competes that trigger when my service ends up being more than 12 months (I have no special skills that would hurt anybody in a specific industry in such a short time). Then I ask for a 3-4% increase in salary, depending on what industry they want me to stay out of. Basically this is my insurance money and reflects my ability to get a job in a different industry.
If the non-compete were for programming in general, it would cost them up to 50% of my salary. A non-compete when I'm on contract will likely cost up to 100% of my normal fee, depending on the duration of the contract. TBH, unless they are already paying through the nose for exclusive access to specialised skills, I've never heard of contract work having a non-compete clause.
Another thing you can/should do is make sure that any exercising/vesting of options/stock carry over into the non-compete period.
Personally, I love non-competes. I use the time for writing free software.
I have refused to sign contracts with non-competes several times in my life. Most companies either remove it or say, "No there's not a not compete. Oh .. huh .. well I'll remove it." I've had two companies fight me over these and I came close to walking away from both, but we ended up being able to work things out.
Most realize they're not enforceable in most states and I've even seen contracts that specify "except in California" since there are laws restricting non-competes there.