Is there a good way to determine which apt packages were installed by the user/admin (as opposed to getting installed by default upon OS install)? The list doesn't have to be comprehensive - can contain both false positives and false negatives but should help in rebuilding the system to current state after reinstall.
Rationale: I've decided my eeebuntu netbook really needs OS reinstall. The original eeebuntu I have installed was a rather early version. Incremental updates fix some problems, reintroduce others. New releases are always more polished than updates to the old ones. Dist-upgrade fails in spectacular manner. Plus I have accumulated a lot of cruft, software I don't need, junk lurking in never-erased temps, and so on. But I'm prety happy with most of software base I have now, and I hate the typical post-reinstall phase of "I don't have this? How quaint, need to install it!". I can backup user data just well but I really need a list of all the custom software I have installed over the years to rebuild it.