Free open source DAW, MIDI sequencer, software synthesizers
Frinika is a free, complete music workstation software for Linux, Windows, Mac OSX and other operating systems running Java. It features sequencer, soft-synths, realtime effects and audio recording.
Audio Devlopment System (ADS) is a multi track audio/midi recording/playback program written in the Java(c) Programming Language. Reqiures Java VM 1.5 or higher. http://java.sun.com/getjava/index.html
Fatamorgana has two goals.
First, provide an implementation of Java's Mobile Media API (MMAPI).
Second, provide resources around MMAPI (examples, FAQ, links).