Awstats
Awstats produces very pretty stats.

Webalizer
is a more complex stats program that produces a nice variety of charts and graphs about who has visited your site. This is probably the most popular stats engine available today.

Subdomain Stats
This will show statistics for the subdomains on your account.

Latest Visitors
This will show you the last 300 visitors who came to your site and some interesting information about them.

Bandwidth
This will show how many bytes your account has transferred.

Error Log
This will show errors in your site, images not loading, missing files, etc. This is very useful for debugging CGI scripts.