Shared Spotify - Find the common songs you have between friends
CodeKeep - Codekeep lets you store and share bits of code and text with other users. Snippets can be organized into folders/labels for instant reuse.
Playlist Souffle - Swap Spotify playlist tracks based on album or artist
Anyfiddle - Build, run and share code in any language from your browser
Songlink - Share music with anyone.
CodeMyUI - Handpicked code snippets you can use in your web projects