FreemindAn innovative application for note taking and outlining. Takes time to get used to, but some people swear by it.
BuddiA personal finance and budgeting program, aimed at those who have little or no financial background.
More Web Browsing
ShiiraFast, nice web browser.
SunriseBrowserGood webkit-based browser created with special tools for web designers.
SeamonkeyFull-featured Mozilla browser, used to be called 'Mozilla Suite'.
Electric SheepImmersive, trippy screensaver.
Tomato TorrentDownload torrents. Nice and simple.
3D Graphics and Modeling
BlenderPowerful 3D Modeling software.
Planetariums and Outer Space
CelestiaOpen-source 3D planetarium software. Akin to traveling through space (outer space).
Stellarium"Renders realistic skys in realtime." See what you would see if your city wasn't so light-polluted. Used in real planetariums.
Simple ComicRead digital comics.
Dance Dance Revolution
StepmaniaDance Dance Revolution clone. Can connect to external dance pads.
CubeNice first-person shooter.
Marathon: Aleph OneEngine for Bungie's free FPS series Marathon. Play online, solo play with rich original story, many total conversions and thousands of maps.
Zombies3D zombie strategy game.
Armagetron Advanced3D Tron game.
BZFlagFirst-person tank game.
Battle for WesnothFantasy / Strategy Game
CocoaliciousLet's you easily post to del.icio.us.
Free File Hosting
CC PublisherHost Creative Commons video or audio files for free on archive.org with this easy uploader.
Viewers Comic viewer: Comical
Comic viewer: FFView
OpenDocument viewing application: ODF Viewer
RSS and Usenet
RSS Reader: Feed
Cross-platform RSS reader: BlogBridge
RSS video podcast player: I/ON
Usenet Reader: OSXnews
IM, IRC, Chat
Powerful IRC client: X-Chat Aqua
Videoconferencing client: XMeeting
PBX / Voip system: Asterisk
Graphics and Art
Draw on a moving canvas: Cosmic Painter
Image editor: Seashore
An artwork scaling calculator: Scaletron!
A Paint-like program designed for pixel-pushers: Pixen
A VRML/X3D Browser: FreeWRL
Realtime Editing and Effects System: Jahshaka
Video transcoder: ffmpegX
MPEG convertor: MPEG Streamclip
Music and Audio
OGG Vorbis encoder (ogg is an open source audio codec): Ogg Drop
Music notation: LilyPond
Play and compose live music: Miraton
Max/MSP style realtime music and multimedia environment: Pd
Manage chords, lyrics, and projection: OpenSong
Wifi / Networking
Discover open wifi networks: iStumbler
A Prism/Prism2 driver 802.11: WirelessDriver
Fast, lightweight VNC client: Chicken of the VNC
VNC server providing remote access to the GUI, keyboard and mouse: OSXvnc
Manage disk space: DiskInventoryX
Book management: Books
CD / DVD Burning: SimplyBurns
Disable sleep on a Mac: InsomniaX
Protect your laptop with a car-alarm style alarm: Multialarm
Remove extra languages from OSX to save disk space: Monolingual
System event notifications: Growl
System performance monitors: MenuMeters
Virtual desktop tool: Desktop Manager
Virus checker: ClamXav
Share mouse and keyboard between 2 or more computers: SynergyKM and Quick Synergy
Check available RAM: Memtest
Monitor CPU, RAM, battery, CPU temp, network, I/O, and more: X Resource Graph
Control your Mac via Bluetooth: Romeo
Writing and Typesetting
Screenplay writing and pre-production support: Celtx
Bibliography manager, BibTeX .bib format: BibDesk
Typesetting - TeX previewer for Mac OS X: TeXShop
Education course management system: Moodle
Student information system: Focus / SIS
Another student information system: Centre
Development platform: Eclipse
SQL Editor: YourSQL
Math and Engineering
General purpose computer algebra system: Yacas
GNU S language: R
MATLAB style rapid engineering and scientific prototyping / data processing: FreeMat