Quick one today guys. When you have your raspberry pi setup up the way you want with all the packages installed correctly and working. You can create an exact copy of your image by simply popping the sd card in to your computer (I’m on a mac) and using dd.
It works like this. When you installed your sd card for the first time your followed a process similar to this: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx
Now we can use the same program we used to write the image to the sd card to copy the image to our hard drive. All dd does, is make a bit for bit copy of one directory to another.
So pop your sd card into your mac and do:
dd if=/dev/disk3 of=~/Desktop/raspi.img bs=1M
If you need to know which disk your sd card is, then run this before and after you insert your sd card and look at the difference: