JHCompo and SolidComposer are no more. Sorry.
JHCompo was a 2-hour, weekly composition competition where entrants created original music based on the theme given. This MP3-based compo was held every Tuesday, and was created as a place for musicians to hang out and hone their craft. JHCompo was all-gear, so you could make your tune with whatever software or hardware you wanted.
All the action happened at SolidComposer (now defunct) including the listening party, which was automated. Entrants would sign up for an account to upload their entries (in MP3 format) to the compo round page. The theme would appear at the start of the compo round. Once the 2-hour round was up, the listening party would start immediately at the compo round page. The compo was open to anyone, from beginners to the well-experienced.