I made my own cable lock setup for my bike. I'm using the high strength cable that I found at home depot that is used to hold several hundred pounds of weight. I forget the exact weight rating on the stuff but it was a pain in the butt to cut. I had to use my dremel to get good cuts on the stuff. It actually ruined a pair of cable cutters that I rented from the store, luckily they didn't charge me for that.... lol.I"ve got one of those cables for my jacket. If I can see my bike most of the time I just leave my jacket/helmet sitting there on or near the bike. If i'm going into a store and it's too hot to walk around with my jacket i'll use the cable to lock it to the bike.
I know those things are easy enough to cut, but crime isn't high here and those who would steal it are looking for the easy grabs.