They state in wordpress.com that blogs in the free version with medium to high traffic can use adwords, but they don't allow javascript in free version. Which is why I can't use Amazon program anymore. I would like to know if one has to pay for ads in adwords, or pay to be in the program. And if you have to copy javascript if you do. And how much of the earnings do you keep, because it says they let you keep most of the earnings, but I don't know how much in percents.