Sullo writes

" Nikto is an open source (GPL) web server scanner which performs tests against web servers for multiple items, including over 3500 po tentially dangerous files/CGIs, versions on over 900 servers, and version specific problems on over 250 servers.

Version 2 adds a ton of enhancements, including:
- Fingerprinting web servers via favicon.ico files
- 404 error checking for each file type
- Enhanced false positive reduction via multiple methods: headers, page content, and content hashing
- Scan tuning to include or exclude entire classes of vulnerability checks
- Uses LibWhisker 2, which has its own long list of enhancements
- A "single" scan mode that allows you to craft an HTTP request manually
- Basic template engine so that HTML reports can be easily customized
- An experimental knowledge base for scans, which will allow regenerated reports and retests (future)
- Optimizations, bug fixes and more...

Source & info:
http://www.cirt.net/code/nikto.shtml