Freeriding:

Bikepark Semmering

Bikeboard.at
Bikepark Map

Pinkbike

Bikeskills

Web Tools:

Cool tool for calculating distances (eg: for your running route) - http://www.gmap-pedometer.com/ 

Flash Games

Shift 2 - http://armorgames.com/play/964/shift-2

Bloxorz - http://armorgames.com/play/539/bloxorz

Play free online games - http://www.kongregate.com/

Hacking Stuff:

Pimp my Shell - http://blog.pimpmyshell.de/

Some Tricks for Linux (german) - http://members.aon.at/astronom/lin_alg.html

Setting up SVN Repository (german) - http://www.schiebler.info/index.php/oliver/linux/6-linux/61-howto-svn-unter-debian-etch-einrichten

VMware Server Hardy Heron - http://ge.ubuntuforums.com/showthread.php?p=4357442

Rebuild Debian ISOs with new kernel - http://kmuto.jp/debian/d-i/

Tips and Tricks for Nautilus (german) - http://wiki.ubuntuusers.de/Nautilus_Skripte

Nautilus Scripts (german) - http://wiki.ubuntuusers.de/Skripte

Nautilus Scripts (english) -  http://g-scripts.sourceforge.net/

Tools:

ClusterSSH

Information Sites:

A Site for all Disney Fans - http://www.duckipedia.de/index.php/Hauptseite

Netzjargon - http://de.wikipedia.org/wiki/Liste_der_Abk%C3%BCrzungen_(Netzjargon)

Friends:
www.happyhacking.at
www.automatisch.cc
www.localdomain.at
www.jeziorny.net

Ubuntu Stuff

Howtos - http://www.ubuntuhq.com/wiki/index.php/Ubuntu_Howtos

Performance Tips - http://ubuntuforums.org/showthread.php?t=189192