Avid readers have long swapped books with friends. Now, with online book-swapping sites acting as middlemen, we can trade books with complete strangers. Although the basic concept is the same, each of the following sites handles the mechanics of postage and mailing labels slightly differently. Take a look at Bookins, and Paperback Swap. For more choices, here’s a longer list of book, CD and DVD swapping sites .

Free audiobooks, podcasts and other educational audio content is popping up everywhere. LearnOutLoud has a directory of over 500 free educational audio and video titles. iTunes has a growing collection of free podcasts. And my local public library has a collection of downloadable audiobooks made available through NetLibrary.com and RecordedBooks.com. Ask your local librarian if your library offers something similar.

Most school and public libraries pay for a variety of premium databases that can be accessed by patrons. Now you can configure Google Scholar to highlight articles that are available through your particular library by setting your Scholar Preferences. Read more at Google Scholar Library Links. Not already familiar with Google Scholar? Here’s an introduction.

Computer books can be expensive, but if you know where to look, you can (legally) download some tech books for free. Here are three resources: Tech Books for Free , O’Reilly Open Books Project, and Bruce Perens’ Open Source Series.

For Harry Potter fans that need a daily dose of Potter news, several sites are now offering their HP headlines in RSS. The RSS format makes it easy to keep up with Harry Potter, without having to individually visit many sites. Here are three Harry Potter news feeds in RSS format: The Leaky Cauldron, Harry Potter Automatic News Aggregator and BBC News: Harry Potter In Depth.

More and more of the best content on the Internet is only available by subscription, but did you realize that many schools and public libraries purchase subscriptions for their community’s use? These subscription sites are generally available over the Internet (with a username and password) so you can even access them from home. Ask your school or public librarian about which online resources are available for your use.

Is your local library catalog online? If it is, you can may be able to find out which books are checked in or out, place a hold on a book, or request an item be transferred from a different branch. To find out, search LibDex ( http://www.libdex.com ) the worldwide directory of library homepages.