Tim Soundtemple has developed a collection of Rozeta patches for composing song in AUM. The suite includes 5 different types of MIDI generators. He plans to release QuantumKomposer soon, after he produces tutorial videos for the individual devices. They will be available for purchase, with some option to try them out before you buy. Tim is still deciding on the exact monetization structure.
There's a lengthy write-up describing the details of each of the devices, along with a discussion on the Audiobus forum. Here is a video preview for QuantumKomposer.
Video Description:
A modular suite of 5 midi generating plugins for composing entire songs in an AUM session