Abyss Web Server X1 is a free web Server available for Windows, MacOS X, Linux, and FreeBSD.
Despite its small footprint, it supports secure SSL connections (HTTPS), download resuming, caching negotiation, logging, CGI/1.1 scripts, FastCGI, ISAPI extensions, Server Side Includes (SSI), ASP.NET (on Windows), custom error pages, password protection, URL rewriting, IP address control, aliases, custom MIME types, index files, custom directory listings, anti-leeching, and bandwidth throttling.
It features also an automatic anti-hacking system and an intuitive multilingual remote web management interface.
With Abyss Web Server X1, hosting your site and your PHP, Perl, Python, ASP, Ruby on Rails, or ASP.NET Web applications is a matter of a few minutes.

Editor review:

Abyss Web Server is a totally free web server with a personal character. Apart from its small size, the Abyss web server has support for CGI and FastCGI scripts, ISAPI add-ons, ASP.NET, SSI, download restarting, cache negotiations, personalized error pages, password protection, IP address controls, index files, personalized directory lists, etc.

Abyss Web Server also has automatic antihacking security measures, and an intuitive and functional web interface, great for experts and novices. Thanks to Abyss Web Server you can store your whole website and your PHP, Perl, Python, ASP, or ASP.NET scripts in a few minutes and without problems.