As a new author on Twek, I’d like to start with a list of my favorite Mac applications.
Tweetie

Just as Tweetie 2 is the best Twitter client for the iPhone, Tweetie is the best Twitter client for Mac. Tweetie is deceptively simple yet extremely powerful.
Cyberduck

Cyberduck is a simple, fast FTP and SSH client. It’s great for SSHing into an iPhone or iPod Touch or FTPing into your own server.
uTorrent

uTorrent is a small, fast BitTorrent client.
ThemePark

Ever wish you could replace Mac OS X’s Aqua theme? With ThemePark and Aqua Inspiriat, you can. Head over to MacStories for the full installation instructions.
Dropbox

Dropbox is software that syncs your files online and across your computers. Put your files into your Dropbox on one computer, and they’ll be instantly available on any of your other computers that you’ve installed Dropbox on (Windows, Mac, and Linux too!) Because a copy of your files are stored on Dropbox’s secure servers, you can also access them from any computer or mobile device using the Dropbox website.