When I realized that I had a lot of redundant scripts, each of them just setting some configuration options for different wlans, I decided to create a more user friendly way for doing this.
Soon after I thought about it, a little shell script came out which reads in config files like this one:
#The variables essid and type are needed essid="YOUR ESSID" #Type can be dhcp or config type="dhcp" #You may specify a WEP key key="YOUR KEY" #If type is "config" you need to specify address,netmask,dns and gateway
Just create one of these file for every wlan you want to connect to and call the script with its name:
$ ./wlan myconf
Everything else will be done automagically.
If you think, hey I need this easy way of configuration for my system, you can download it below.