It's an online phenomenon that has already taken American bookworms by storm and is now rapidly catching on across the UK.
Three new UK-based book swap sites have gone live in the last year alone – worldwide, there are many more.
The concept is simple. Join a site, register books you no longer want and then offer to swap them with other users for new books you haven't read.
Hey presto! A new book arrives in the post and that novel that's been gathering dust on the bookshelf for months gets an appreciative new owner.
It's a kind of Napster for bookworms, back when Napster was free and membership spread via word of mouth.
How it started
The first known UK-based wesite to offer book swapping over the internet was ReadItSwapIt.
The site was invented in 2003 by two young British entrepreneurs, Neil Ferguson and Andrew Bathgate, in the hope that it would encourage book swapping in the UK.
Despite incurring costs running the site, they have never charged members anything and now boast over two thousand books.
"We wanted to create a site that would enable people to gain access to hundreds of books, without having to spend any money," said 26 year-old ReadItSwapIt co-founder Neil Ferguson, a computer programmer who began building the site while off work for 10 days with chicken pox.
The site has just attracted its 500th member. It remains the only completely free book swap club in the UK which has no plans to start charging members.
Others, such as MyBookYourBook and LetsdoaSwap which both went live less than six months ago, intend to charge a small membership or swap fee.
There's also The Book Cooperative (used by libraries), Swapz and Swap-O shop, which were set up in the last 18 months, and US-based Paperback Swap, Book Relay and Title Trader.
Each site offers a slightly different service to the online bookswapper. While some offer direct exchanges with other users, others work on a credit system, allowing users to swap books for credits that they can then use to acquire books (or other products) at a later date.
Read, recycle AND get a bargain
The explosion of sites has been welcomed by book charities and conservation organisations.
Environmental charities like Friends of the Earth and Leep Recycling have praised the book recycling element of sites like ReadItSwapIt to their members while Scottish Waste Awareness Group and the National Literacy Trust are currently directing book lovers to ReadItSwapIt via their websites.
Traditional book industry
There's no point denying it – book swapping is bad news for local bookshops and book publishers. After all, book swappers never run out of books to read, without having to spend a penny buying new books.
In an attempt to fight back, online bookshops are coming up with new strategies to target members of bookswapping sites.
Amazon, for example, is offering site owners a percentage of new books bought by their members at Amazon – so if a desired book isn't available for swapping, members will often be re-directed to Amazon.
Ethical Christmas Giving Books rank among the top Christmas gifts of all time. But why waste money and trees buying new books to give away this Christmas?
Book swapping sites provide people with a new, ethical way to shop for books this Xmas.
"Christmas is about giving, not spending money, and that's really what my book swap site ReadItSwapIt is all about," said Ferguson.
Online book swap clubs are also a great way to get rid of books that are unwanted Christmas gifts – members can swap these presents for books they actually want to read instead.
So if you're giving a book as a gift this Christmas but you're not sure the recipient will like it, be sure to mention book swapping.
After all, whatever the future holds for bookshops, it's clear book swapping is here to stay.