How long do you stay 'on hold' before hanging up?

I once stayed on hold well over an hour, possibly over two.  I was reporting a power outage during a blizzard.  ConEn thanked me for my patience...my area had not yet been reported, so had I hung up, we would have been even longer without power.  

I would say it depends on who you're calling.  If you're reporting an emergency situation, stay on the line.  If you're holding for your cable company, 15 minutes is the max I would hold.

I've had to wait something like two hours when I've called the Social Security office. I didn't have much choice in the matter because I knew the hold times would always be bad and I needed to talk to them. With less sensitive/ urgent matters, I max out at about ten minutes. Sometimes five.

  It depends what I'm on hold for. If it's important I'll hold as long as necessary. If not important, I'll usually give it 15 or so minutes.

Pretty much what everyone else is saying here.  I will hold for a government office because I have no choice.  It can be a long wait.  If it's a doctor's office, I will wait up to 10 minutes and call back. 

I don't wait well.  The answer would depend on how badly I needed to have the anticipated conversation.

Lol, do you see that, folks?  I made her wait at least ten minutes this time. I'll teach her not to file restraining orders against me!