Internet

Adium
A simple all in one AIM, chat client. Supports, Gmail, Hotmail, Yahoo and many other through the use of plugins and basic support. It does lack some functionality in some chat protocols.

ApGrapher
A great little program that offers the ability to find information about the wireless networks whizzing around your head.

Azureus
One of the best bittorrent clients out there. Has lots of user extensions through the use of plugins.

Colloquy
A really powerful application that can be used for the IRC networks. Special care has been taken in this application to make it blend in with the rest of the Mac OS theming.

CSSedit
A must for any web developer. CSSedit offers the best tools around to help you edit and modify CSS code for you webpages.

Cyberduck
A small lightweight application for ftp. Has some small niggles, but it is free. Transmit is better if you use ftp a lot.

Firefox
One of the best web browsers around in my opinion. Has a massive add-on library which you can customize to your needs. A viable alternative to safari.

iStumber
I found this a great small application that enabled you to view wireless and bluetooth networks quick and hassle free.

LittleSnitch
The application that snitches on any application that is trying to access the net to phone home. Great for protecting you privacy.

Netnewswire
A very popular RSS client for the mac, nuff said.

Skype
Offering superior calls over the internet, it is the application if you do a lot of talking and want a good quality transmission.

Transmission
A light weight bittorrent application that is gaining popularity. Its personal choice at this point of transmission verse Azureus.

Transmit
A great application from Panic that will feature a couple of time in this list. It is a powerful application for ftp uploads and downloads.

Undercover
A piece of software that dials to the undercover servers if you computer has been stolen. Great if you use a laptop, less useful on a desktop.

Unison
Another piece of panic software that enables you to use the usenet newsreader networks. A really good piece of software if you use usenet a lot.

Vidalia
A GUI controller for the Tor anonymity network. One click on, one click off, simple and easy to use. Best of all its free.