I haven't purchased or rented any movies through iTunes, so I don't know how it works. I have a feeling it does NOT work like this, but I wish that it did. It would be nice if whenever you rent a movie on iTunes it went as a sort of "credit" towards purchase of that same movie. Meaning if the movie costs $20 and I were to rent the movie for $5 to watch it once. If I decide after I've seen it that I would like to buy it, it would be nice to only have to pay $15. If I've rented it twice it would only cost $10; 3 times it would cost $5, and 4 times it would be free essentially (technically cost 3 cents because each rental is actually $4.99). I don't see any problem with such a scenario. The only issue I can see is that it would discourage purchasing, but I think that encouraging renting would counterbalance that. Plus a lot of people are much more hesitant to buy a movie for $20 that they've never seen, but they might be more likely after they rented it. Thoughts?