Have you gone to long before cleaning up the local apt cache and freeing up space in /var?
Is your attempt at cleaning house in your local apt cache failing like this?:
booooxen:/var/lib# aptitude clean Reading package lists... Error! E: Dynamic MMap ran out of room
You can try to up the limit here:
APT::Cache-Limit 50000000; (add it to /etc/apt/apt.conf (or some sorta file called): /etc/apt/apt.conf.d/70debconf on Debian