I just updated my Amazon Widget (on the right side of the page) with all the books I am currently reading. For those of you who don't know me, I read a lot of books at the same time. I find that it appeals to my short attention span and also allows me to absorb and apply what I read better. The books I read at the same time are all from different categories of my life and personal goals.
The first 4 are ones that I read as part of my quiet time. The next 6 are my morning reading. The next 6 are the books I read at night (usually only 3 or 4 nights per week). There are two others that I read occasionally. I typically red 5-10 minutes per book depending on how much time I have.
I have been reading this way for years and I find that I get a lot read and keep my interest up. I probably read 50-60 books per year this way. Mixing the topics is a key part of the plan.