Update to DMT
From the website, "Create orchestrations of up to 8 staves, and enter notes by clicking them into the staff or importing MIDI or MusicXML files. Once your music is in NotePad, you can hear it play back, see it on the printed page, and share it with other NotePad and users of other Finale family music notation software." This is free software.
Incredibox - http://www.incredibox.com/
Incredibox is a set of fun loop generators. You select from a set of beats, effects, choruses, and voices to create your loop. In the second, third and fourth version of the generator it is possible to record your mix for sharing and downloading. (Downloading your loop costs $0.99 per loop.)
Otomata is a digital musical sequencer. You can create a sequence of looping tones by clicking boxes within a grid. Each box may move in one of four directions. If any two boxes collide they will change direction by 90 degrees, creating unique sequences. The site allows you to record and download your loops as a WAV file for free.
Soundation hosts an online audio editor, similar to GarageBand. The editor allows you to save projects and has loops/clips to add in to your projects. You can also record audio from though your computer. When you care finished, you may export your projects as WAV files. All of this function is free, but you may pay for premium sound clips if you desire.