Wicd is an open source wired and wireless network manager for Linux which aims to provide a simple interface to connect to networks with a wide variety of settings.
Some of Wicd's features include:
1. No Gnome dependencies (although it does require GTK), so it is easy to use in XFCE, Fluxbox, Openbox, Enlightenment, etc.
2. Ability to connect to wired and wireless networks
3. Profiles for each wireless network and wired network
4. Many encryption schemes, some of which include WEP/WPA/WPA2 (and you can add your own)
5. Remains compatible with wireless-tools
6. Tray icon showing network activity and signal strength