List Your Handy Mac Apps.

So after being inspired by The Verge's Best Mac Apps Article, I thought I'd ask the community what apps they couldn't live without?

I don't think I could revert back to a OSX without Alfred, and Tweetbot has become second nature to me. But I'm far more interested in whatever knowledge you have to share on the subject of useful features. :)

So hey, if you like an app that you think deserves more coverage, shoot it off here.

(Also, this is my first Forum post ever, so I apologise in advance for my shoddiness and general lack of writhing talent)