Magic Playlist - Get the playlist of your dreams based on a song
Felt for iPhone - Handwritten cards for the modern world
Spotalike - Spotify playlist with similar songs, according to Last.fm
Thankster - Automagically send hand written cards
Playlist Machinery - Tools that help you create & organize your Spotify playlists
Handwrytten - Handwritten notes straight from your device. Huge selection of cards or design your own. Handwriting service integrates with 1000's of apps.