If you've ever wondered exactly where your favorite web services get their funding, a simple and handy website called "How do they make money?" will show you the revenue breakdown of over 40 services from a variety of companies. In addition to a quick analysis of income sources, the website addresses Silicon Valley's harshest benchmark: profitability. While the source of the site's data appears to be Seer Interactive, a marketing and analytics firm, no citations are immediately available. Questionable data sources aside, "How do they make money?" is a fun way to check on the financial underpinnings of your favorite online services.