Bookcrossing.com, a Missouri-based book tracking system, has caught on worldwide, but State College has more books in the wild than anywhere else in Pennsylvania, according to the Web site.

In the vein of such Web sites like www.wheresgeorge.com -- which allows users to track dollar bills -- bookcrossing.com serves as a medium for strangers to update the progress of books they've hidden.

As of right now there are 439,945 members registered.

"It's just a hobby," member and Penn State employee Susan Gordon said. "It's fun."

Gordon runs and maintains an official Book Crossing zone at Stone Soup, 1011 E. College Ave., Suite C, a grocery store that sells local products. She said that Book Crossing -- a shelf of books free for the taking -- is starting to become a fad in State College.

"It's been slow starting, but it's picking up some," she said. "State College is a very literate area."

Gordon said she saw a mention in Reader's Digest about Book Crossing but did not think anything of it until her sister said something.

"My sister who lives in Cumberland, Maryland, got excited about an official zone," she said.

Once a book is taken for a zone it should be posted on the Web site, but Gordon said it does not have to be.

"You can participate and be completely anonymous," she said.

Once the book is finished, Gordon said, it can be left anywhere for someone to find.

"You can leave them any place," she said. "Restaurant bathrooms or doctor's offices -- any place where there is a lot of people."

Stone Soup has an entire bookcase where someone can just take a book home, said Stone Soup co-owner Sally Sherman.

"When do you really get anything for free anymore?" she said.

Sherman said that Gordon approached her about creating a zone at Stone Soup after a friend of Gordon's suggested the store.

"The idea had instant appeal to me," Sherman said. "Susan briefly explained the concept, and as a book lover, I said yes."

Sherman said that Gordon maintains the bookshelf and makes it appealing to the customers.

Sherman said that there is everything from Anne Rice to the Q'uran and admits to taking a few of the books and replacing them. "I have indulged myself surreptitiously and honestly," she said.

At Webster's Bookstore Café, 128 S. Allen St., co-owner Elaine Meder-Wilgus said she does not think Book Crossing would hurt her business. People will always want to buy books, regardless if they can get some on loan, she said.

"People have approached me about starting one here," she said. "But they never followed through."

Meder-Wilgus said it may sound counterintuitive, but she would allow for a Book Crossing zone to be set up in her store.

"Books are like food to me," she said. "Sometimes you go out and pay and sometimes you cook for other people."

Meder-Wilgus said she likes to make Webster's more than just shopping.

"Of course we have to sell things," she said. "But I want people to have a place for discussion."