editor for the past couple of weeks and I've really enjoyed it. At first there weren't very many extensions/packages available, but the community has been quick to fill in that gap.
You can browse the packages online or from Atom's Preferences... (⌘,)
GitHub has included serveral packages in the base install of Atom and in addition they've created other helpful packages as well. Some of the more helpful packages I've found are...
Vim Mode - "Provides vim modal control for Atom, ideally blending the best of vim and Atom."
Editor Stats - "View a graph of your mouse and keyboard activity for the last 6 hours."
In addition, the community has really stepped up and have written a lot of packages in a very short amount of time.