Rocketgraph - Rocketgraph is an open-source drop in replacement to Firebase, except it's much better.
Plug - Lightweight OSX player for Hype Machine
Muru Music - Personalised playlists within seconds.
Flamp - Reviews of companies in your city.
Standard Notes - A safe place for your notes, thoughts, and life's work
Magic Playlist - Get the playlist of your dreams based on a song