Chef for configuration files. Customisations for Chef Attributes are in a json.php file on the chef host that merges various things like specific settings for a datacenter, host role, etc.

Google Docs for certain information as well as a wiki. There are Standard Operating Proceedures (SOP's) for numerous tasks also in the wiki which explains things in detail.

Munin for graphing along with some metrics being polulated into Zabbix.