I looked into this open-source sublime-like text editor a long time ago and it was underwhelming. Now that it's a 1.0 release I looked into it again and... it has a live markdown previewer. I'm in love already.
Git diff highlighting is pretty cool too.
To me, the killer Sublime Text (and subsequently Atom.io) functionality is the multi find/edit/insertion point. Multiple times a day this helps me get quickly to a result.