1. Adium
This free application allows you to use pretty much any instant messaging service you may be signed up for, and be signed into these services all at the same time. Whether you use AIM, Yahoo, MSN, Facebook Messenger, or other services, Adium has you covered.

2. Alfred
Alfred is a free application that allows you to do tasks like launch applications, search your Mac, do simple calculations, and issue system commands, all by using a keyboard shortcut instead of using a mouse.

3. Skitch
Skitch has long been one of our favorite apps on the Mac. This app lets you easily take and edit screenshots, or capture a photo directly from the camera built into your Mac or Cinema Display. And now that it's a part of Evernote, it's free!

4. Tiny Expander
Compressing and expanding ZIP files is a feature that’s included with Mac OS X. However, sometimes you may need to deal with weird files types that your Mac cannot access by default. In this case, turn to Tiny Expander. This free utility can handle expanding files in over 25 different compressed formats.

5. Gmail Notifier
If you’re like us, then you love Gmail and Google Calendar, especially the online user interface. But, if you’re like us, then you definitely don’t love having to keep your browser window opened all the time. Enter Gmail Notifier. This menu bar app notifies you via alerts whenever you get a new email or have an upcoming Google Calendar event.

6. Transmission
Torrents are great, so long as they’re perfectly legal ones. And, if you like torrenting, then you should be using the best torrent application on the Mac: Transmission. This app has all the bells and whistles, including the ability to manage your torrents remotely on an iOS device.

7. Virtualbox
Switching to the Mac, but cannot give up on some of your Windows applications? Don’t fret over spending tons of money on a virtualization platform like VMWare or Parallels. Simply use the free Virtualbox application to virtualize just about any OS. Be sure to check out our guide on using Virtualbox.

8. Perian
Play those pesky Windows Media files and other arcane media types on your Mac with this free plug-in for QuickTime. Perian isn’t called the “Swiss-army knife for QuickTime” for nothing. Installing this System Preference pane will let you play AVI, DIVX, FLV, MKV, Windows Media, and other non-supported file formats right inside of QuickTime Player.

9. Breakaway
If you listen to a lot of music on your Mac through iTunes, then you will definitely appreciate this little utility. If your headphones happen to unplug, this app will automatically pause iTunes, mimicking the functionality of the iPod. With this app installed, you’ll no longer have the awkward stares as ABBA begins playing loudly. But seriously, what's wrong with ABBA?

10. Onyx
Your Mac automatically and periodically runs tasks that help keep things running smoothly. However, you may want to run these tasks manually at will. For this, use Onyx. And besides running maintenance tasks, you can also enable the hidden features of your Mac.