As I'm running my own server I though it would be interesting to monitor various parts of the site and server that it runs on. The main tool is MRTG, which is an excellent piece of software freely available under the GNU General Public License. I use this to monitor the traffic through my router, CPU utilization and internal temperatures of the server. As time allows I might try to add what I'm graphing using this excellent tool.
Additionally using another tool webalizer I'm generating stats from the webserver log file.