For all of you who like wargames and the pentesting target distros (like those from de-ice, etc,) check out http://roothack.org.  They host rootwars and other games on there, for both individuals and teams, and there's much fun to be had, while socializing with others of the 'hacker' variety.

Additionally, for those wanting to learn and polish your hacking skills, there's more 'individual' fun to be had in the Games - Sirens page.  There, they have an ssh gateway, leading to 2 more servers, with everything from basic hacks to things like buffer overflows, etc.  The Sirens games were evidently originally posted for a security mini-conference held for Novell's employees, a couple of years ago, and they have since made them available to the public.  I've not taken the time to get through all of the exercises on there, yet (you'll see me on the scoreboard, about a 3rd of the way through the more advanced target box, at 130 points) but it's a good refresher.

Anyway, hope others find it both useful and enjoyable!