I don't claim any originality with this post. Have a look at Joshua Boissevain's great piece of curation, where he ponders the use of unmanned (model) helicopters to help journalists in difficult areas. Might come handy in Athens, Tehran, Madrid, etc. I wonder if the police would attempt to shoot it out of the sky? It would certainly help get more accurate estimates of crowd sizes. They are often inflated by the organisers and deflated by the authorities or opposing side.