I use an OnGuard Mastiff (similar to that Fuggedaboutit posted upthread) and a Knox U-lock. I always park in the same spot, so I leave the locks locked to the rack at work. If I'm making a quick stop on the way home I'll bring the U lock along. My bike parking is supposedly video monitored, so I figure the giant chain will prevent anyone from really spending any time trying to liberate my Cross Check, not when there are about 10 less well locked and more attractive looking mountain bikes nearby.