The folks over at Flowtown have revised their original infographic to reflect the social buying boom. Here's the new revised infographic:
What can we tell from the above? Well first of all that space is nascent and so are its physics; First movers aren't necessarily rewarded. Woot, which was founded in 2004, currently has over 1.4 million unique monthly visits versus dominant player Groupon's (which was founded in 2008 and pivoted to the model) 29.1 million.
Second runner up LivingSocial is around half the size of Groupon, at 14.3 million unique monthly visits, with 301 US cities to Groupon's 182. Yeah that's about 5% of the US population visiting the site monthly.