The Turnabout Twins, by Barbara Hazard. It's an old Signet Regency Romance from the early 80's that I enjoyed in paperback, and was happy to find as an ebook.
I've added The Fabric of the Cosmos by Brian Greene to my five book reading stack. I usually just grab the book at on the top read 10 -20 pages, put it at the bottom then pick up the next book. Rinse and repeat until I get back to the first book then it's off to sleepy bo-bo's.