When you start the Tor Browser Bundle, there are several links for help on Tor. I don't know what the link for Atlas is. It has many graphs on the output node and the firewall ports allowed and blocked. What is this?
From the Tor Project description:
Atlas is a web application to discover Tor relays and bridges. It provides useful information on how relays are configured along with graphics about their past usage.
This is the spiritual successor to TorStatus, the original codebase for which was written in PHP, and rewritten by students from Wesleyan as Django.
Basically it's a web application that provides useful information on how relays are configured along with graphics about their past. When you click the link from the TorCheck page in Tor Browser it gives you the configuration/history of the exit node you're currently using.