VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVD, Audio CD, VCD, and various streaming protocols. It can play almost ANY type of video file.

http://sourceforge.net/projects/vlc/files/1.1.10.1/macosx/vlc-1.1.10.1.dmg/download

Handbrake - DVD ripper with MPEG-4 / H.264 encoding. The simplest way to save DVDs on your computer.

http://handbrake.fr/downloads.php

Burn - Burns to DVD, VCD, and SVCD. Take your downloaded videos and burn them to disks you can watch on regular DVD players. For VCD and SVCD you don't even need a DVD burner. Free and open source!

http://burn-osx.sourceforge.net/Pages/English/home.html

Transmit - The best FTP program for Mac.

http://www.panic.com/transmit/

Dropbox - Automatically backup your files and folders via the internet. Share them across your own computers or with others. 2GB free online storage, with more available.

https://www.dropbox.com/

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!

http://wakaba.c3.cx/s/apps/unarchiver.html

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.

http://qsapp.com/

Senuti - Transfer music from your iPod or iPhone to your computer with this easy to use application for Mac.

http://www.fadingred.com/senuti/download/

Seashore - "Photoshop" your photos without buying Photoshop. 100% free and open source, based on the open source image editor "Gimp".

http://seashore.sourceforge.net/The_Seashore_Project/Download.html

Adium - Why install three separate instant messengers when you can connect to AIM, MSN, Yahoo and GoogleTalk in a single, beautiful app? Plus it's 100% free and open source. Everybody needs Adium.

http://adium.im/