inTreble is a music collaboration application with many features. It provides REALTIME multi-user experience for both composing and playing music on over 88 instruments.Here are some of the additional features available for PRO members:
Import/Export MIDI files
Export Sheet Music/MP3/Ringtone
Share Tracks anywhere with track URLS
Compose with Sixteenth,Eighth,Quarter,Half and Whole notes.
Realtime playing with friends.
Use a Harp, Piano, or wave your hand to make music.