SpeakerBlast.com turns devices into a massive (or small) stereo system; all devices play same audio at the same time via a web app. Works solid on Wifi & 4G!
In this SpeakerBlast 50 people & their devices blast audio in sync at the Baltimore TechBreakfast meetup.
Thanks to @elithecomputerguy for the video & to @tech_breakfast for having us!
