There are a bunch of tools that we find invaluable as a developer.
We love f.lux! f.lux adjusts your screen's brightness depending on the lighting and the time of day / sun level in the sky, for ease on your eyes and to help you sleep. Play around with the settings. It's subtle, but makes a huge difference, especially if you're working late on your computer.
You should have a quick launcher so that you can run applications and arbitrary commands through a keyboard shortcut.
Alfred 2 - This is my favorite, but it costs money to unlock the very required power features. But I use this around 92 times a day. Plus it comes with a clipboard history. There are lots of power user guides for all this software.
Quicksilver - tried and true and free and awesome. but so old.
Launchbar - People love it, I've never used it, and I think it costs money.
There are lots of power user guides for all this software.
If you do not have a clipboard history enabled...well, I mean, that's just crazy. The one in Alfred is awesome. Others include:
Collective - Looks awesome, super cheap ($2), have never used it.
Jumpcut - Free but old.
ClipMenu - Free.
Dash - A comprehensive documentation browser. It's awesome, will save you hours in googling. Costs money, but worth it.
DevDocs - A free Dash alternative
Github OS X - Worth having, but honestly, I've never used it.
SourceTree - Super heavy git gui that's free and pretty good.
GitX (L) - A well maintained fork of GitX
You're going to be spending a ton of time staring at your screen. The default fonts you have installed probably aren't the most readable. Here are some nice ones you may want to consider installing:
View Supporting Software on Learn.co and start learning to code for free.