On Monday at the Graphing Social Patterns conference, I moderated a panel about making money from Facebook apps, with Giles Goodwin of Widgetbox, Hooman Radfar of Clearspring, and Jeff Nolan of Newsgator. It's a complicated question, especially for companies that have existing Web-based businesses. When do you start work on a Facebook app? Will a Facebook product cannibalize your other Web products? Can an online business survive on Facebook exclusively?