: For my TV shows delight. It automatically downloads the .torrent file and opens my torrent download client when a new favorite show appears in the net.
Adium: My favorite IM client. Using the Marten-Plain White menu bar icons set.
Sparrow: Best desktop Gmail client. Period.
Skitch: I love Skitch for quick capturing and sketch notes. I use in conjuntion with Droplr (see below) because I prefer a shared image page without much clutter.
Alfred: Applications launcher on steroids. I really like the command customization, and the Powerpack rocks!
Dropbox: Should I describe it?
Droplr: It let you store images, files, texts and short URLs by just dragging anything to the menubar icon. I mostly use it with Skitch to capture -> drag -> get link.
PasteBot: Copy and paste directly to my iOS devices.
: Only for quickly adding events/reminders to my Google Calendar, I don’t use the Gmail notifier because Sparrow manages it just fine.
Typinator: A really useful text expander tool, for quick snippets and signatures.
MagicPrefs: Enhanced functionality for my Magic Mouse and Macbook Pro trackpad. Haven’t tried other alternatives, but it works amazingly.
Evernote: Love to have everything stored in one place. Even my bills and tickets. Syncing with all my devices is the best thing.
Caffeine: Because my Mac also needs a dose.
: Very cool alarm clock with nice features like use your own music, and less intrusive than Awaken. And best of all, free!
Radium: Best online radio player for Mac. Only lives in your menubar, no useless windows. Just plays the radio and also scrobbles to Last.fm.
And the Apple ones: Time Machine, Bluetooth, Airport, Sound, Battery, Hour and Spotlight.
(From Leandro Ardissone)