have you tried
aptitude purge ~c
before packing it back together?
localpurge is installed per default on mint, isnt it?
i think you may have a look in /var/log for ***.gz files, but on a fresh install its useless.
my first thought was removing gparted, as its quite big when its getting installed, but removing it didnt free much of space. As you said: a good (=easy) choice would be replacing OO with abiword. If theres a second kernel..., but i dont think there is. The gtk2-engines are quite a bunch of MB, iirc. firefox and thunderbird are quite heavy too. cups. java (for whatever it is good for i dont know
...what i would try.
its not that easy, as some packages are big when getting installed but dont give you profit when removing them. Check in synaptic, and remove them from the terminal (apt-get remove --purge packagename) and you will be told what you win. If it aint much choose no and keep the package. Everything gnome depends on as a metapackage will give you ( a bit of ) trouble.