While my previously released Compendiaria included Wlan setup it proved to be troublesome under Debian family. The troubles were due to the reason that I designed Compendiaria when I was using Arch/Gentoo systems. As Debian is quite different from those two here is a Wlan setup program that was designed for Debian family.
Download the original wlanset.zip program from this link and then unzip the archive.
To use the program you should have wpasupplicant and wireless-tools installed (sudo apt-get install wireless-tools wpasupplicant)
Run the program as a sudo (use sudo su) or as a root user inside a terminal client.
3th of February 2015:
Wlansetup updated to a version 0.3.1-Audax
The update fixes a typo, which caused misbehavior on /etc/rc.local if there were already some lines present in it. Now Wlansetup should add the autostart line nicely to the end of /etc/rc.local.
*Note. If you get weird errors when using usb wlan sticks try another usb port. I had one usb port, which gave me plenty of errors and refused to start the interface scan of Wlansetup correctly – all other ports worked just fine.