That is actually a really good example. Look at the competition, Conduit (http://techcrunch.com/2008/01/16/toolbar-company-conduit-rai...), a company that literally has a few hundred employees (150-499 according to Glassdoor). I figure that Google has about the same number as the competition does for each service, so the Chrome team would roughly match Mozilla (~300 employees), the Docs team would match Zoho (~1500 employees), Maps would match MapQuest (~150 employees), etc.

Not to nitpick, but Zoho also has portfolio of several other products including Accounting, CRM, Helpdesk, Network Manager among others. And their total employee strength as you said is ~1500.