After running his West Loop property as a weekend diversion for two years, he quit his investment banking job in 1998 and began working toward a business degree.

FORBES: Life

If Foursquare can subtly create brand associations and social media product placement in a non-obtrusive way, it may stand a chance, but to do so requires an OODA loop running at a much faster pace with a more diverse view of the marketplace.

FORBES: Is Foursquare's Bubble About To Burst?

This speed-climbing technique is known as running a PDL (or Pakistani Death Loop, purportedly named after an unfortunate South Asian climber who took a huge fall off the Nose attempting to break the record).

WSJ: El Capitan's Nose in a Day | By Michael J. Ybarra