[skizm]

From what I gather, they're one of the few video conference solutions that "just work", you don't need to install anything if you don't want (works in the browser), and their user pricing is pretty cheap and straightforward ($15/mo/user). Also, they've scaled well as there haven't been too many (any?) major outages, even though their usage has gone up probably 50x (complete guess) in the last 1-3 months.