Here is p0f “sales pitch” from it’s website.
What is p0f v2?
P0f v2 is a versatile passive OS fingerprinting tool. P0f can identify the operating system on:
- machines that connect to your box (SYN mode),
- machines you connect to (SYN+ACK mode),
- machine you cannot connect to (RST+ mode),
- machines whose communications you can observe.
P0f can also [...]

Nikto Homepage: http://www.cirt.net/code/nikto.shtml
Description: Nikto is an Open Source (GPL) web server scanner which performs comprehensive tests against web servers for multiple items, including over 3300 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 [...]

What is JanusVM?
JanusVM is software that allows you to surf the Internet without oppression or censorship, while protecting your privacy, security, and identity. It has advanced filtering capabilities for modifying web page content, managing cookies, controlling access, and removing ads, banners, pop-ups and other obnoxious Internet junk. JanusVM was designed to used on Microsoft Windows [...]

Run multiple operating systems, including Windows, Linux, and Solaris, on your Macintosh at the same time as Mac OS X – without rebooting. Designed from the ground up for the Mac, VMware Fusion allows you to run Mac and Windows applications side-by-side – quickly and effortlessly sharing information between the two operating systems’ environments.
http://www.vmware.com/beta/fusion/index.html