AYRT: So far it's been busiest in the evenings US time. Coordinating something with other timezones is tricky, and probably impossible during the week. If people sleep between roughly 1am and 8am, and have weekday commitments from around 8am to 6pm, here's what the situation looks like:

http://i.imgur.com/gDNSDRp.jpg

The boxed hours could be a good time to get most people together on weekends. (Sorry Australians.) If people are around today we could try 12pm USA west/3pm USA east/8pm UK?