How to keep track of the installed software/system configuration to restore after a fresh linux install?

I have been thinking of writing some sort of utility for linux that keeps track of all my installed software and configuration. Something that after doing a fresh install I can just run it and will restore my copy of ubuntu as it used to be before doing the fresh install.

I do not know exactly where to start with this. I know that you can get a list of user installed software from dpkg -i | grep ii.

I would really appreciate any suggestions.