I've had to cut loose a number of bikes that had OnGuard locks 'cuz they froze. I've also sent out a number of customers with a hammer and a bottle of spray lubricant to knock their lock loose so that I don't have to charge them $50 for going out and cutting their lock. As much as I really don't like Kryptonite, their locks, in my experience, work the best.
At Interbike I saw some Pinhead mini locks that looked pretty cool. The key is the same as the ones they use on their locking skewers. I think the locking skewers don't work THAT well as I know of at least two ways to defeat them (one of which they're working on solving, the other of which we couldn't convince them was enough of a problem to actually fix). Their mini lock though had the same style key, but the little pins were behind a shield.