This is a comment by Christopher Billich (the link somehow doesn't work - gives me an 404 error). He gives a good summary on Mobagetown business model: Thanks Chris.
Comment on mobagetown business model: The way they set it up - drawing people in with free games, who then get involved in the SNS part of things, including their avatar (who needs to be outfitted by means of the virtual currency they give out to members for clicking on ads and purchasing things online) - is indeed very clever. What is even better, and mostly overlooked though, is the fact that mobagetown's parent company DeNA a) operates several mobile shopping and auction sites that mobagetown drives users to in huge numbers and b) runs one of the biggest mobile affiliate advertising networks in Japan, Pocket Affiliate, which makes a lot of its money through ad placements on mobagetown, but also serves to promote mobagetown through placements across its affiliate network (think: Google Ad Words/Ad Sense, in a way).