Danger Sense: Think more Intuitively (Insidious GURPS Planning)
My Danger Sense is Tingling (Gaming Ballistic)
Gamemaster's Guidepost: GMing Danger Sense (Ravens N' Pennies)
My Thoughts on Danger Sense
I wish my players took it more, to be honest. I try to have capable foes act like capable foes, which means that ambushes, traps, and other sudden surprises are fairly common in my games. Danger Sense really takes an edge off of these, and I think eases the tension level a bit. I don't really oppose that, as I have any number of ways to make the players sweat, so taking the edge off of a threatening situation doesn't bother me. It's also a 15 point advantage based off Perception, so it's a bit of an investment and a PC should really get their points worth.
I do have a bit of a problem at times remembering someone has it, or forgetting to roll for it when appropriate. This is especially bad in this case as it's really a roll I have to make myself as the GM. Nothing can put your players in alert mode like saying "Make a Perception roll." I need to come up with a visual aid of some sort to hang on my GM's screen to remind me of it.
As far as the "Metagame Points" that Doug Cole and Christopher Rice bring up in their posts, I'm not as much of a fan. I've been using Buying Successes for a couple of years now, and I'm starting to think that they just don't suit my style as a GM. That's a bit strange because I've always allowed retroactive Luck rolls, but for some reason I find an expensive and time-limited advantage less irksome than a cheap "Get Out of Jail Free" card.