Mac Apps You Don't Know How You Lived Without?

Go. What are you apps that have changed your productivity/life?

Aside from the obvious for a graphic designer (illustrator and photoshop)

Quicksilver is a great app to save a bunch of clicks.

I just started using Evernote. I am just getting used to the in's and out's so time will tell if it becomes a "second brain" for me.

Fantastical is a pretty great calendar app.

Your turn!