(I did not "invent" this idea, someone told me about it. I figure you'll be interested in the experience, it was rather surprising for me.) Google makes money on ads, oodles and oodles of it. Up until today, I never "understood" the value of ads. Today, I got a chance to use ads, here is my story: Dropbox is a storage service, if your friend signs up by clicking your referral URL, both you and your friend get 250MB of free storage up to 8GB of storage. This means if you can get 32 (8GB/250MB) friends to sign up you get lots of free storage. As you can imagine, I don't have 32 friends,...