I've written little script for downloading all TurnKey appliances. It's not great, fast or superportable. Just download two attached files, make get executable and run it. You need wget and command line ;) If the mirror is slow, just find your own and change it in the script.
I don't know if there is any other way to download all TK appliances at once, my googling wasn't successful. If you know about some other way to do this quick, please let me know in comments. Maybe this'll help somebody out.