I will not rent anything that can be copied losslessly. (Among other things, this is the major reason I don't have netflix.) And I consider anything that can be (legally) taken from me without my consent, or that I cannot legally reencode, to be rented.

"Buying" an ebook currently is effectively renting it. If/when that changes, if/when I can actually buy an ebook, I will start buying ebooks.