Is there any hacking simulation game on the net?

http://www.cyberarmy.com/ has little hacking challenges and such, starting simple. I've never actually bothered going through their challenges, but you might find it interesting.

Uplink. dunno where u get it. word of warning, it isnt realistic, its more of a game.

Uplink = http://www.introversion.com/

http://www.hackquest.com/

http://www.try2hack.nl/

http://www.reverser-course.de/