… or why sometime the solution is so obvious that I' am unable to see it.
I was recently set up my other Raspberry Pi to be a pentesting box, just for the sake of doing it. So I dd'ed the image to the SD card, stated the Pi and was unhappy. I wasn’t able to use the whole SD card. Only the original image size was available to get used by me.
So how to solve it?
I asked the world wide web and found something, but it didn’t worked out for me. I' am pretty sure it was me doing the procedure wrong. But anyways - My problem wasn’t solved. After a bit of further search the net I found an easy solution. I didn’t documented the link, but the steps.

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wget http://http.us.debian.org/debian/pool/main/l/lua5.1/lua5.1_5.1.5-4_armel.deb
wget http://http.us.debian.org/debian/pool/main/t/triggerhappy/triggerhappy_0.3.4-2_armel.deb
wget http://archive.raspberrypi.org/debian/pool/main/r/raspi-config/raspi-config_20121028_all.deb
dpkg -i triggerhappy_0.3.4-2_armel.deb
dpkg -i lua5.1_5.1.5-4_armel.deb
dpkg -i raspi-config_20121028_all.deb

For those of you how are a bit familiar with the Raspberry Pi and the offered operating systems offered for it: “YES, you can simple install raspi-config and run it. And yes truly obvious!”
So the solution to my problem was to simply install & run raspi-config and use the functionality of it to resize and use the complete SD card.