VLC media player

The VideoLAN - VLC media player is a free, cross-platform media player. It supports a large number of multimedia formats, using its own codecs and can be used as a streaming server, with features such as video on demand and on the fly transcoding. It's available for Windows, Mac OS X, BeOS, and Linux.

WinDirStat

"WinDirStat (WDS) is a disk usage statistics viewer and cleanup tool for Windows. It shows disk, file and directory sizes in a treelist as well as graphically in a treemap, much like KDirStat or SequoiaView."

Steve Bass from PC World writes:
"Find colossal files the quick and easy way. Then dump erase them to save disk space."

The SourceForge project is here.

QCad - The CAD System For Everyone

An inexpensive, simple and relatively powerful 2-D CAD package. We have used it quite successfully to create formula-driven drawings to feed our CNC controlled plasma cutter.

"QCad is an application for computer aided drafting in two dimensions (2d). With QCad you can create technical drawings such as plans for buildings, interiors, mechanical parts or schemas and diagrams. QCad works on Windows, Mac OS X and many Linux and Unix Systems. The source code of the QCad community edition is released under the GPL (Open Source)."

Wikipedia entry

SquirrelMail - webmail for nuts

SquirrelMail is a standards-based webmail package written in PHP. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 (with no JavaScript required) for maximum compatibility across browsers. It has very few requirements and is very easy to configure and install. SquirrelMail has all the functionality you would want from an email client, including strong MIME support, address books, and folder manipulation.

Note: The hMailServer installation includeds two plug-ins for SquirrelMail. One password changer that lets users change their own password via the client, and one auto-reply plug-in that lets user set auto-reply messages when they are out of office.

hMailServer

hMailServer is a free, open source, GPL-licensed e-mail server for Microsoft Windows. It supports all the common e-mail protocols (IMAP, SMTP and POP3) and comes with an easy-to-use COM library that can be used for integration with other software. It also has support for virtual domains, distribution lists, antivirus, antispam, aliases, distributed domains and much more. E-mail data is stored in a database server, MySQL or MS SQL, depending on your choice.