Below is a list of FOSS that run on Windows, Linux, & other operating systems

Design

BLENDER
Blender is an advanced 3D modeling program capable of producing high quality animations, performing rendering, post-production, interactive creation and playback. It is the only 3D creation suite which allows the artist to model, texture, animate, render, and export the finished product in a package less than 10 MB.

GIMP
The GNU Image Manipulation Program (GIMP), is a powerful and comprehensive imaging solution, suitable for those wanting to manipulate digital photographs, design and export graphics for the web, convert from one file format to another and even produce complex high-resolution compositions for print. The GIMP features a number of paint tools with sub-pixel sampling for high quality anti-aliased brush strokes, a powerful gradient editor and blend tool, layers and layer masks with over 20 blending modes, support for importing and exporting in a myriad of image formats, unsharp mask, levels and curves tools for enhancement of digital photos and much more!

INKSCAPE
Inkscape is an Open Source vector graphics editor, with capabilities similar to Illustrator, Freehand, CorelDraw, or Xara X using the W3C standard Scalable Vector Graphics (SVG) file format. Supported SVG features include shapes, paths, text, markers, clones, alpha blending, transforms, gradients, patterns, and grouping. Inkscape also supports Creative Commons meta-data, node editing, layers, complex path operations, bitmap tracing, text-on-path, flowed text, direct XML editing, and more. It imports formats such as JPEG, PNG, TIFF, and others and exports PNG as well as multiple vector-based formats.

SCRIBUS
Scribus is an open-source program that brings award-winning professional page layout to Linux/Unix, MacOS X, OS/2, and Windows desktops with a combination of "press-ready" output and new approaches to page layout.

NVU
Nvu (pronounced en-view) is the open source world's answer to Macromedia's Dreamweaver. It is a fully featured what-you-see-is-what-you-get web page editor, enabling you to create compelling web pages without having to devote months to learning HTML. Nvu includes an integrated FTP site manager, a style sheet editor, tabbed workspaces, and all the features you've come to expect from a fully-featured web page editor. Nvu also features integrated support for HTML code validation, to help you make your HTML as clean and light-weight as possible. Because Nvu is built based on the award-winning Gecko rendering engine that also powers the Firefox web browser, every moment is a live preview: what you see is truly what you get.

Internet

FIREFOX
Firefox light-weight web browser based on Mozilla technology. It empowers you to browse faster, more safely, and more efficiently. Key features include: Popup Blocking to stop those annoying ads popping up. Tabbed Browsing lets you view multiple web pages in a single window. Open links in the background so that they're ready for viewing when you're ready to read them. Text zooming is a quick way of enlarging or decreasing the text of any web page to make it more readable. You can expand this lightweight core by adding plug-ins that do everything from automatic form completion to blocking Flash animations.

THUNDERBIRD
Thunderbird is a modern email client with features such as intelligent spam filters, a built-in spell checker, a range of themes and customisable layout. Thunderbird provides IMAP/POP support, HTML e-mail composing, quick search, address book, advanced message filtering, address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts. With Thunderbird Extensions you can add additional features to help you build a mail client that meets your specific needs. As with Firefox, security is a central theme. Thunderbird provides enterprise and government grade security features such as S/MIME, digital signing, message encryption, support for certificates and security devices. The intelligent Thunderbird spam filter analyzes your e-mails to identify those that are most likely to be junk. These can be automatically deleted or diverted to a separate folder. The spam filter is adaptive and also learns from your address book and usage to improve its accuracy.

PIDGIN
Pidgin is an instant messenger (IM) client. Use it to chat with others in real time using any supported network, including AIM, ICQ, MSN Messenger, Yahoo!, IRC, Jabber, Gadu-Gadu, and Zephyr. Gaim can be simultaneously connected to several networks, so if you have contacts on different networks, you can talk to them all at the same time, from one easy to use program.

Multimedia

AUDACITY
Audacity is a sound editing program which can record, playback, and mix sounds or apply effects using a variety of filters. Edit your sounds using Cut, Copy and Paste (with unlimited Undo) and mix multiple tracks together. Save your files in a number of formats, including WAV, Ogg Vorbis and AIFF, or use Audacity's native project format for high performance editing. MP3 support is available using the external LAME MP3 encoder, which is included with CDex, or can be installed from here after installing Audacity. It also has a built-in amplitude envelope editor, a customisable spectrogram mode and a frequency analysis window for audio analysis applications. Built-in effects include Bass Boost, Wahwah, and Noise Removal. This full-featured program is fast and stable, and is also available for Linux and MacOS X.

Productivity

OPENOFFICE.ORG
OpenOffice.org is a full-featured productivity suite including a word processor, spreadsheet, web page editor and presentation program. Notable features in this version are native PDF and Flash export at the click of button and a macro recorder for increased productivity. OpenOffice.org provides you with the ability to create mail merged documents from Outlook or Mozilla address books, spreadsheets, or other data sources and its tightly-integrated modules help to simplify work flow. Documents are stored in a compressed, open-standard XML format to ensure future availability of your data and to reduce file sizes. You can read and write documents in a wide range of formats including Microsoft Office.

OPEN WORKBENCH
Open Workbench is an open source desktop application that provides robust project scheduling and management functionality. Already the scheduling standard for more than 100,000 project managers worldwide, Open Workbench is a free and powerful alternative to Microsoft Project.

PDFCREATOR
Use PDFCreator to generate PDF documents directly from any Windows program. PDF (Portable Document Format) files are the de facto standard in electronic publishing, because the author can be sure that the document will look as intended on all platforms, regardless of local fonts or lack thereof. PDFs can also be generated with commercial packages, but PDFCreator is by far the easiest and cheapest option (free). Once installed, simply select 'Print' from the File menu of your word processor or drawing program, and select 'PDFCreator Printer' from the list of printers. Click 'Save' and enter a name for your PDF output file. That's it!

Operating System

UBUNTU LINUX
Ubuntu is a community developed, linux-based operating system that is perfect for laptops, desktops and servers. It contains all the applications you need - a web browser, presentation, document and spreadsheet software, instant messaging and much more. Ubuntu is free software.

Utilities

7ZIP
7-Zip is a program for creating or unpacking archived and compressed files. It can unpack 7zip, ZIP, CAB, RAR, ARJ, GZIP, BZIP2, TAR, CPIO, RPM and DEB files, or create file archives in those formats. For the standard ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2 - 10 % better than that provided by PKZip or WinZip, and the native 7zip format can provide a 45% reduction in file size from the common zip format. The program is highly configurable, allowing the user to balance the level of compression and speed. The interface is designed to mimic the standard Windows shell, Explorer, and is localized to 40 languages.

CLAMWIN
Clamwin is a free anti-virus software for the Windows platform.  It features free updates of virus signatures.