Back in January, each branch of the Chester County Library System received seven Nook e-readers to circulate. So far, they've been a hit, according to Malvern Librarian Rosalie Dietz.

Each Nook is specific to one genre—mystery, romance, science, fiction, thrillers, fiction, nonfiction, biography—and comes pre-loaded with numerous titles.

"They're still popular," librarian Rosalie Dietz said. "We never have more than one on the shelf here."

What's the one genre usually left on the shelf? The answer is surprising, considering it's a high-tech gadget:

"The least popular is science fiction. We usually have that hanging around here," Dietz said. "The most popular are fiction, mystery and biography. I've never seen [fiction] since we started circulating them in February."