Roland 808303.studio - TR-808 drum machine and TB-303 bass synthesizer emulator
triqtraq - Are you a DJ or electronic music producer?
Sampulator - Make (and record) beats on your keyboard
Figure - Propellerhead creates world-class software products and services that inspire music makers and provide the foundation for a worldwide creative musical community.
Audulus - A universe of sound at your fingertips - Audulus is a modular music processing app
Wavepot - Wavepot is addictive music or beats maker platform that offers a live-coding environment for creating sound and music.