Nikto

Nikto is an Open Source (GPL) web server scanner which performs comprehensive
tests against web servers for multiple items, including over 3200 potentially
dangerous files/CGIs, versions on over 625 servers, and version specific
problems on over 230 servers. Scan items and plugins are frequently updated and
can be automatically updated (if desired).

Nikto is a good CGI scanner, there are some other tools that go well with Nikto
(focus on http fingerprinting or Google hacking/info gathering etc, another
article for just those).

Get Nikto Here - http://www.cirt.net/code/nikto.shtml