Dropbox — Probably the most brilliant gem. I use the 50GB Pro plan.ClipMenu — My choice for clipboard manager. Pretty simple app with a lot of custom options.Caffeine — Click it to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers.CloudApp — A well-known one. Allows you to share images, links, music, videos and files. Also, automatically uploads your recent screenshot and copies the link ready to share.BaseApp — Helps you stay on top of everything that happens in your Basecamp accounts. I use Basecamp in my work and I’m tired of the inbox overflowed with Basecamp notifications. Let BaseApp do it. From creators of CloudApp.Growl — The one and only notification system for Mac. Should be built-in.DisplayPad — Allows you to use your iPad as a second display for your Mac. There’s a variety of such apps, but this one seems to be the best.Twitter — Official Twitter app.LittleSnapper — Allows you to capture screenshots, organize them or annotate and share. This tool has a very nice and native interface and, as a UI designer, I use it a lot for capturing some inspiring elements. The rest are built-in ones: Keyboard, Clock and Spotlight. (From Gadzhi Kharkharov)

Dropbox — Probably the most brilliant gem. I use the 50GB Pro plan.
ClipMenu — My choice for clipboard manager. Pretty simple app with a lot of custom options.
Caffeine — Click it to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers.
CloudApp — A well-known one. Allows you to share images, links, music, videos and files. Also, automatically uploads your recent screenshot and copies the link ready to share.
BaseApp — Helps you stay on top of everything that happens in your Basecamp accounts. I use Basecamp in my work and I’m tired of the inbox overflowed with Basecamp notifications. Let BaseApp do it. From creators of CloudApp.
— The one and only notification system for Mac. Should be built-in.
DisplayPad — Allows you to use your iPad as a second display for your Mac. There’s a variety of such apps, but this one seems to be the best.
— Official Twitter app.
LittleSnapper — Allows you to capture screenshots, organize them or annotate and share. This tool has a very nice and native interface and, as a UI designer, I use it a lot for capturing some inspiring elements.
The rest are built-in ones: Keyboard, Clock and Spotlight.
(From )