Desktop
Emacs
The editor to end all editors. Or the OS in need of a good editor, depending who you ask. Editing modes for every language, markup, conf file out there.
org-mode
https://www.youtube.com/watch?v=oJTwQvgfgMM TODO lists, GTD, hierarchical notes, et al.
Improved puppet-mode
https://github.com/ilikejam/puppet-syntax-emacs/commit/133afcd48f4e7188561981072c19c57644c1eb0d Now apparently superseded by a different module, but if you like the original Puppetlabs mode there might be some nice changes in my patch branch
Terminal (OSX)
The default terminal app on OSX is Just Fine. Even does middle-click paste.
urxvt (Linux, Windows)
https://wiki.archlinux.org/index.php/Rxvt-unicode Fast, unicode and TT font support, resizing works. Most of the time
Airfoil (OSX)
https://rogueamoeba.com/airfoil/ Send audio to chromecast, airplay, and bluetooth from individual apps (or the system) to multiple sinks. Combine with Chromecast Audios (sadly discontinued now) for dirt cheam multi-room audio.