Emrecan Dogan has a good analysis of content rental business models. He's created a simple framework for evaluating the dynamics of renting different types of content, and he's taken as examples books, textboks, music, movies, video games and software.
Of this list, the software example has attracted my attention. I think Emrecan's talking about shrink-wrapped software. He's attached it an average price point of $90. And he concludes that the rental market potential is low.
This made me think of Software-as-a-Service models, which are frequently thought of as rental models. But when you approach it using Emrecan's framework, SaaS looks more like a subscription/service model than a true rental model.
Maybe it's just a semantics issue but I have seen so many cases where SaaS is treated like a rental approach that I thought the difference is worth noting.