Kongregate's Emily Greer and Anthony Pecorella presented a talk called "Core Games, Real Numbers" at GDC this week, delving into virtual goods games on Kongregate and what drives their success, including all sorts of juicy stats and advice. We've received a lot of requests for the slides so here they are:

GDC 2012 - Core Games Real Numbers Final by Emily Greer on Scribd

Here's more on Kongregate's developer program if you're interested in how we work with developers.