This started with the simple question "how exactly does package X pull in package Y when I install it". The only way I knew of was to use aptitude interactively and just guess which package was the most likely culprit.
Kurz-HowTo: Eigenes sichereres Debian-Repository aufbauen
Compare of different tool to set up a Debian repository
debian paket wetter *hüstel*
Ubuntu Tricks - how to generate a list of installed packages and use it to reinstall packages