Open Source Mac - A simple list of free, open-source software for Mac OS X.
Free and open-source software is good for you and good for the world. This is the best free Mac software that we know of.

Web Browsing

firefox

Mozilla Firefox

The premier free, open-source browser. Tabs, pop-up blocking, themes, and extensions. Considered by many to be the world's best browser.
Download Page

Video Player, Torrents, Podcasting

miro

Miro

Beautiful interface. Plays any video type (much more than quicktime). Subscribe to video RSS, download, and watch all in one. Torrent support. Search and download from YouTube and others.
Download Page

IM - Instant Messaging

adium

Adium

Connect to multiple IM accounts simultaneously in a single app, including: AOL IM, MSN, and Jabber. Beautiful, themable interface.
Download Page

Video Converter, iPhone Converter

video converter

Miro Video Converter

Convert any type of video to mp4 or theora. Convert any video for use with iPhone, iPod, Android, etc. Very clean, easy to use interface.
Download Page | Mac App Store (free)

Telephone

Telephone

Telephone

A great "SIP" client. Call regular phones from your Mac. 100% free and open source.
Download Page

Financial Transactions

bitcoin

Bitcoin

A "peer-to-peer" digital currency so you can buy things without paying transaction fees.
Download Page

Application Launching

quicksilver

Quicksilver

Quicksilver lets you start applications (and do just about everything) with a few quick taps of your fingers. Warning: start using Quicksilver and you won't be able to imagine using a Mac without it.
Download Page

Email

thunderbird

Mozilla Thunderbird

Powerful spam filtering, solid interface, and all the features you need.
Download Page

Utilities

The Unarchiver

The Unarchiver

Uncompress RAR, 7zip, tar, and bz2 files on your Mac. Many new Mac users will be puzzled the first time they download a RAR file. Do them a favor and download UnRarX for them!
Download Page

DVD Ripping

handbrake icon

Handbrake

DVD ripper and MPEG-4 / H.264 encoding. Very simple to use.
Download Page

RSS

vienna

Vienna

Very nice, native RSS client.
Download Page
rssowl

RSSOwl

Solid cross-platform RSS client.
Download Page

Peer-to-Peer Filesharing

cabos icon

Cabos

A simple, easy to use filesharing program. Gnutella network.
Download Page
solarseek

SolarSeek

Soulseek filesharing for Mac, in a simple, solid client.
Download Page
transmission icon

Transmission

Very nice torrent downloader.
Download Page

Running Windows Software on Macs

Q

Q Emulator

Run Windows programs on your Intel Mac at near native speed. Works on G4 / G5 Macs too, but much slower.
Download Page

Podcasting

juice

Juice

Solid podcasting client.
Download Page

Video Playback

VLC

VLC

Plays more video files than most players: Quicktime, AVI, DIVX, OGG, and more. Pretty good interface.
Download Page
MPlayer

MPlayer

The interface and buttons are not as nice or as Mac-like in feel, but it may play even more video files than VLC.
Download Page
MPlayer

Perian

A plugin that allows quicktime to play additional video formats. (Included in Democracy Player.)
Download Page

iPod Ripping

iPodDisk

iPodDisk

Copy music off your iPod in the finder, like a regular disk drive.
Download Page

CD / DVD Burning

handbrake icon

Burn

CD and DVD Burner. Burn any video to a disc that plays in your DVD player!
Download Page

Privacy

vidalia

Vidalia

This TOR frontend keeps you anonymous on the web using military-grade techniques. For use with Firefox see: TorButton.
Download Page

Word Processing / Office Suites

libreoffice

LibreOffice

Big, full featured suite of tools for word processing and spreadsheets. Compatible with and a free replacement for Microsoft Word, Powerpoint, and Excel. Friends don't let friends pay for Microsoft Office.
Download Page
abiword

AbiWord

A word processor. Leaner and quicker than OpenOffice. Compatible with Microsoft Word documents and OpenDocument Format.
Download Page

Wifi Scanning

kismac

KisMac

The best wireless scanner for Mac. Find wireless access when you're on the go.
Download Page

Sound Recording

audacity

Audacity

Simple sound recording tool.
Download Page

Graphics, Photo, Publishing

gimp

Gimp.app

Photo editing application that rivals Photoshop in features.
Download Page
formulate pro

Formulate Pro

An easy way to fill-out (or sign) PDFs that Preview can't edit.
Download Page
Xee

Xee

Fast image viewer and image browser.
Download Page
inkscape

Inkscape

Vector graphics application (requires X11).
Download Page
scribus

Scribus

Desktop publishing. Complicated install, but a nice app.
Download Page

FTP / SFTP

cyberduck

Cyberduck

Very good all-around ftp program.
Download Page
onebutton ftp

OneButton FTP

Simple, fast FTP, with a focus on "advanced queuing".
Download Page
fugu

Fugu

Not as polished as Cyberduck (and only for SFTP) but has a side by side interface showing your files and the remote files.
Download Page

HTML / Text Editing

Blue Griffon

Blue Griffon

Visual tool for making websites (WYSIWYG html editor), comparable to Dreamweaver.
Download Page

IRC

colloquy

Colloquy

Great IRC client.
Download Page
colloquy

KVIrc

A cross-platform IRC client that's free and open source.
Download Page

Web Development

wavemaker.gif

WaveMaker

A visual development tool for building great-looking web and cloud applications.
Download Page

A project of Space Inch