F/OSS solutions are great, they give you everything you need to get just about any task done. This is a list I will try to maintain for some the the best F/OSS tools for getting things done. The solutions on this list should pretty much all be multi-platformed, meaning that there should be a version that runs on the major desktop platforms of Linux, OS X, and Windows. Your experiences may vary depending on the OS you run. I also have create sections on F/OSS solutions that are specific to the Linux, OS X, and Windows environments.

Office / Productivity

OpenOffice.org [Office Suite]- One of the most important tools in any computer users toolbox is their office suite. Typically one of the first applications all users learn to use, the office suite in multifaceted and one that you become completely dependent on. From early on we are pretty much brainwashed into thinking there is only one product out there for this, a rather expensive set of proprietary programs that quickly established itself as a staple “must have” application on most computers, and there was a time, a long time back, when this might have been true.For a few years the Open Source community worked on building replacements, some of which are still around, but them Sun Microsystems open sourced a product they had acquired called StarOffice and things just took off. The maturity of this projects has sky rocketed over the last couple of years and now offers a feature set that is pretty much on pace with the proprietary solutions that are out on the market.

Thunderbird [Email Client]- Now a days many people live in their email program. I used a lot of these clients and Thunderbird in pretty much on par with them. One of the strong aspects which Thunderbird brings to the table is it’s extendability. It’s from the good people of the Mozilla project whose name you will see to continue to pop up on this list. Thunderbird pretty much has everything you would expect from a mail client, filters, spam controls, the ability to manage RSS feeds, etc. One place Thunderbird falls short is the ability to tie into exchange, Thunderbird only works with IMAP and POP accounts (to my knowledge).

Lightning [Calendar] – Remember when I mentioned earlier about how Thunderbird is so nice because of its “extendability”? Well this is actually that. Lightning is another Mozilla project that is meant to bring calendaring functionaility to Thunderbird. This project does a fair job and letting you manage multiple calendars as well as online calendars. It doesn’t have quit the intergration as some of the calendaring systems that come bundled in some OSes but it does a good job and allows you to move from platform to platform and maintain functionality and familiarity with the application.

Internet

Firefox – Probably one of the biggest success stories in Open Source next to Linux itself is Firefox. Firefox is a web browser. Yet another solution brought to us from the Mozilla project . Firefox is the worlds second most popular browser. Firefox was born from the Mozilla browser which was an Open Source implmentation of the old Netscape web browser. As typical of the other Mozilla project, Firefox has the concept of being extended by Add-Ons. A lot of features we have in all browsers, find there way there through Firefox.

Filezilla – A FTP client that supports FTP, SFTP, and FTPS (FTP over SSL/TLS). FileZilla was started as a computer science class project by two classmates. Before they started to write the code, they discussed on which license they should release the code. They decided to make FileZilla an open-source project, because there were already many FTP clients available and they didn’t think that they would sell even one copy if they made FileZilla commercial.

Communications

Pidgin -Pidgin (formerly named Gaim) is a multi-platform instant messaging client. The software has support for many commonly used instant messaging protocols, allowing the user to log into various different services from one application. The number of Pidgin users was estimated to be over 3 million in 2007.

XChat – XChat is a full-featured IRC client and includes all basic functionalities that are found in most other IRC clients, including CTCP, DCC file transfers and chats, and a plugin system for various languages (including at least C or C++, Perl, Python, Tcl, Ruby, Lua, CLISP, D, and DMDScript). By writing plugins, one can extend the features and customize the functionality of XChat.
I have some personal confusion around the state of XChat on the Windows platform. Heard a rumor it was no longer Open Source.

Graphics

GIMP – The GNU Image Manipulation Program, or GIMP, is a free graphics editor and is typically thought of as a free software version of Photoshop. This isn’t really a field I have any real talent in. I struggle using GIMP about the same as I struggled using other solutions like Photoshop and Fireworks. I barely scratch the surface on programs like GIMP but I have not come across anything I “couldn’t do” in GIMP.

Inkscape – Again, this is really out of my wheelhouse but Inkscape is a free and open source vector graphics editor application. Its stated goal is to become a powerful graphic tool while being fully compliant with the XML, SVG and CSS standards.

Multimedia

Audacity – A free, easy-to-use audio editor and recorder. You can use Audacity to record live audio, convert tapes and records into digital recordings or CDs, edit Ogg Vorbis, MP3, WAV or AIFF sound files, cut, copy, splice or mix sounds together, change the speed or pitch of a recording, and much much more.

I can not stress to you enough how this is a very small sampling of Free and Open Source Software solutions. I would strongly recommend you to look and the application you use the most and do a little research on what the Free and Open Source solutions for those programs are. Here is a good place to start:  http://en.wikipedia.org/wiki/Portal:Free_software/categories