It´s always good to know how your wireless network could be attacked and secure it accordingly. Cracking WEP and WPA Wireless Networks explains how to use aircrack and kismet to work with WEP encrypted networks as well as static passkey WPA or WPA-PSK.
The first paragraph starts with a little theory on WEP cracking and goes on with setting up your tools, finding the network, capturing IVs, Using IVs to decrypt the key and finally Anticipated Problems. After that the differences between WEP and WPA cracking are explained and the article informs you about different WPA flavours.

Essential Wireless Hacking Tools
Backup Wireless Networks
Connecting to Wireless Networks in GNOME
Wireless Network Scanner inSSIDer
Wireless Migrator
Great artical, I new nothing of cracking WEP before this, with in a short time I had cracked my first one!
Great link