Bosca Ceoil - A free, easy to use tool for creating music.
OnlineSequencer.net - OnlineSequencer.net is an online music sequencer that allows users to create beats and music tracks.
Zynewave Podium - Podium is a modern digital audio workstation (DAW) for Windows.
AudioSauna - AudioSauna is a full-featured audio workstation for making music online.
Renoise - Renoise is a digital audio workstation.
GoatTracker - This is a crossplatform C64 music editor.