As you can tell from recent blog posts, I have been spending time looking at traffic sources for various sites (Facebook, Huffington Post, Perez Hilton, etc). New data from Hitwise reveals that one-third of Foursquare's traffic comes from Facebook:

Top traffic sources for Foursquare 1. 33% Facebook 2. 22% Google 3. 08% Twitter In total, nearly two-thirds of Foursquare's traffic arrives from three sources (one search and two social).

A few things pop out:

- Facebook's referral traffic has steadily grown on a relative basis... and considering that Foursquare's SEO 'juice' has most likely strengthened over time, that means the relative growth has overcome success on Google.

- Twitter as a traffic source is relatively volatile: large peaks around 30% and lows around 7%. It is likely an outcome of power Twitter users and large events (like SXSW - though not reflected here).

- I imagine the visits differ dramatically between Google and Facebook + Twitter. SEO likely sends more branded ( and deep visits (directly to locations - ie a specific venue's name); whereas Facebook and Twitter are more social and circular (driven by the individual rather than the location).