No one has mentioned it in the post, so I'll go out and say I'm a fan of Pinheads on top of a solid U-lock. Everything is hackable if given the time and knowhow. In that sense, everything is more a deterrent than anything else (or an incentive for the thief to pinch the wheels of the bloke next to you). I'm not a fan of cable locks unless they're pretty thick but that's a pain to haul...