Targus ASP29US DEFCON 1 Retractable Cable Lock

Comment:
Compared to some of the smaller locks it's a bit on the big-and-bulky side, but looks aside it works beautifully. The cable retracts fairly quickly so be careful nobody is standing too close to you when you retract it or they'll have some nice bruises. The hidden adapter storage area is a nice touch too. All in all, I'm quite happy with it.