Dependency graphs
Andrew blogs about this nice Debian Dependency graph generator over at gnowledge.org.
It nicely shows why I'm not entirely fond of the belgian electronic ID software: just have a look at the dependency graph for libbeidlibopensc2. Seriously.
These are very easy to create for yourself without the need for using this website:
apt-cache dotty [package] > foo.dot dot -Tpng foo.dot > foo.png
You will need to install the "graphviz" package in order to get dot. Try the same with neato. In order to mimic the output from the website only a few changes to the dotfile need to be made.