I don't lock my bike at all, ever. There have been a half dozen times in the last 3 years when I would have liked to have locked it, but for a couple of times a year it's just not worth carrying a lock. I have one, it's a cheapo $6 combo lock from KMart. I don't doubt it could be broken with almost any tool, but I'm sure it would be enough to stop anyone around here; bike theft just doesn't happen here.

A little one like that gun lock looks interesting though; I could fit that in my tool bag and forget about it except for the 2 or 3 times a year I actually feel that I should lock the thing.

If I'm just running into a store for a few minutes and can park the bike by a window, I don't worry about it. The people in the stores around here are usually close to the windows and I say hi to them when I walk in, and I'm pretty sure if someone else messed with my bike they'd raise hell. If I go into a supermarket or a big box store or something where I'll have to leave the bike outside where nobody can see it, it'd make me a little more comfortable to be able to put a little lock on it, though honestly I think the odds of it getting stolen are pretty low.

The stores around here are all isolated, there's pretty much no way to get there without driving, so anyone that's there has a car and is unlikely to go stealing bikes.