It would seem that the Kindle Fire is doing well: Amazon says it's selling more than a million total Kindle devices a week, and the Fire sits atop its best seller lists. Mobile ad platform Millennial Media has offered up some more specific numbers, however: it's found that the Kindle Fire is racking up "hundreds of millions" of monthly user ad impressions. The company says that the growth of impressions on the Fire has been growing by 19 percent daily — faster than the first iPad when it launched. Of course, we don't know how the Fire stacks up to the iPad now, and we'd love for Amazon to release any hard numbers on individual Kindle sales, but for the moment it appears Jeff Bezos has a hit on his hands.