debtree allows you to generate graphs using graphviz.
First checkout code from the source repository todo that execute following command.
git clone git://git.debian.org/~fjp/debtree.git
Now cd into the directory debtree. And execute following commands to generate sample graph
./debtree dpkg > out.dot dot -T png -o out.png out.dot gnome-open out.png
Enjoy the dependency graphs.