From the outside it appears that many of the YC companies try to stake out a territory, amass a user base with a free service, and then sell or find some other

From the outside it appears that many of the YC companies try to stake out a territory, amass a user base with a free service, and then sell or find some other way to make money. It seems like we don't hear much from those guys--they must have some valuable, hands-on experience to share.