Since I debootstrap a lot, I download the same base packages from the debian server over and over again. This sucks as it eats up the bandwidth of the debian people and is slow for me. The solution is apt-cacher that acts as a local debian repository and totally automagically even works for foreign architectures or distributions.
After apt-getting it, the only things I did to make it run, was to edit /etc/apt-cacher/apt-cacher.conf and /etc/default/apt-cacher. In apt-cacher.conf I had to remove the asterisk from the allowed_hosts setting and also set generate_reports to 0. Then setting AUTOSTART to 1 in the default file and from that point on I just have to use the following repository mirror URL in my bootstrapping scripts:
The beauty is, that I dont have to configure apt-cacher to source http://ftp.de.debian.org beforehand - it's all done by a request of the above style. Would I want apt-cacher to choose a different mirror, I would just request another url from it. This way I can transparently cache any debian mirror I want without any hassle.