Productify - Sell your WordPress content using Gumroad
Bootstrap Zero - Open-source, free Bootstrap templates collection.
Additor beta - Pocket and Evernote got a minimal and collaborative baby
Bootstrap Magic - Create your Bootstrap 4.0 themes easily with magic
Typeboost - Music stops when you stop typing. Stay focused while writing
Material Design for Bootstrap 4 - Powerful and free UI KIT for the newest Bootstrap 4 and Material Design