Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
OnlineSequencer.net - OnlineSequencer.net is an online music sequencer that allows users to create beats and music tracks.
GarageBand - GarageBand is a fully equipped music creation studio for Mac
AudioSauna - AudioSauna is a full-featured audio workstation for making music online.
Adobe Audition - Mix, edit, and create audio content in Adobe Audition CC with a comprehensive toolset that includes multitrack, waveform, and spectral display.
Jummbox - A modified Beepbox that have more stuff then Beepbox. It can be used just like Beepbox. The features of Jummbox is the same of Beepbox's features, but Jummbox have more stuff to offer.