The rule is: You don’t do what’s already done. If you’re a 4-5 person startup with limited resources and little time in hand then you don’t mess around with testing small stuff, you concentrate on the main startup idea. Now if you have any past development experience then you surely know that sending out invites and importing contacts from your user’s hotmail, yahoo or Gmail’s address book is crucial and you don’t want to mess with that. So how about getting help and doing it with just a few API calls? This is what CloudSponge.com really is: They help you pull email address contacts from your user’s address books with just a few API calls. It’s a SaaS (Software as a Service) based model and really affordable for startups running tight on budget.