Inside Higher Ed reports that the number of students who rent textbooks is increasing. Interestingly, e-books have not caught on — most students are still using printed textbooks (though iPads might change that).
When I teach intro, I have always suggested to my students that if they are going to major in psychology, it is a good idea to purchase and keep their intro textbook. My argument has been that it will be a good reference for their upper-division classes, which might assume that they already know certain concepts. For example, when I teach an upper-division class in motivation and emotion, I assume that my students understand classical and operant conditioning (and I tell them in the syllabus that they should go back to their intro textbook and review the relevant sections).
A downside of this advice is that textbooks are very expensive. Renting a book, or selling one on the used market after the term ends, is a way for students to reduce costs.
Anyway, what this got me wondering is whether it’s still helpful or necessary for students to keep their intro textbooks. Is there enough good info on the internet now that they could just google whatever topics they need to review? A few years ago I looked around on the web for a well-written, introductory-level account of classical conditioning and wasn’t impressed with what I found. I still don’t think I’d assign the current entry for classical conditioning as a review. But with the APS Wikipedia project, for example, maybe things will get better soon.
I remember finding my intro textbook especially helpful when I studied for the psychology GRE, but not many undergrads will go on to do that. Next time I teach an upper-division class I’ll probably ask my students how much use they’ve gotten out of their intro text afterward.
The Hardest Science 
I used my intro text for GRE Psychology studying, too. I never used it for my upper division undergrad courses, though. I have occasionally used it when meeting with undergrads in my office (mostly because I am working with a lot of neuroscience and physiology undergrads who don’t have the basic psych background), but other than that, I haven’t touched it. And this is from someone who got a PhD in psych…
I am fine with the trend towards renting (in everything, really, netflix, pandora, etc etc).
But unfortunately, I don’t like the attitude that often goes with it; where quality content is devalued in favor of what is easier.
When it is that much easier to go to Wikipedia, rather than access the textbook (even if it is often relatively easy to borrow an intro textbook, doesn’t every department have hundreds of these things?) I think students go with Wikipedia (or a random youtube clip, for that matter) rather than the textbook.
I guess I don’t care if they rent the textbook, as long as they come out of the class realizing that a textbook (any textbook) is going to be a far more credible source than Wikipedia, youtube, or About.com (often in the top ten google results).