How to check Ubuntu crash log in last session?

My headless Ubuntu (11.10) crashed. When I plug in keyboard and monitor, I see an non-interactive cursor (no blink) on a black screen. SSh, telnet don't work from other machines. Ping works.

I have restarted the machine. How could I check the log files of the last session, so I can know more about this crash?

On Ubuntu (running 13.10 as of this day), the /var/log/apport.log contains crash log messages, which is rotated per configuration in /etc/logrotate.d/apport. The actual crash reports are saved in /var/crash/ -- Not sure how relevant this information is with regard to other releases. Also, this may only be true with apport enabled (https://wiki.ubuntu.com/Apport#How_to_enable_apport).