These site have some hacking type wargames, great fun and good to learn by.
http://www.dievo.org/
http://www.hackerplayground.com/games.php
http://hackerslab.org/
http://www.hackergames.net
http://roothack.org/
Hack Dot AE
Update: (04/20/2005)
Hackquest.de
hackthissite.org
honeynet.org
http://quiz.ngsec.com/
http://www.slyfx.com
http://www.mod-x.co.uk/main.php
http://www.osix.net/
http://www.bright-shadows.net/
http://academy.dyndns.org/
http://ambience.digitalshell.net/~llamatron
http://www.blind-dice.com
http://www.learntohack.org
www.area-6.net
If you know of some other sites let me know and I will add them here.
– Suramya