Books:Americabookshelf.com – One of the largest book exchange clubs across the US.
BooksConnect – A book sharing community site connecting readers, authors, publishers, librarians and booksellers.
BookCrossing.com – A community of users from over 130 countries who exchange books with each other at public places like cafes, parks etc.
Bookhopper.co.uk – Free community for UK residents to share used books with each other.
Bookins.com – Book sharing website that enables members to exchange used books with each other in real time.
BookMooch.com – An interesting concept where users can exchange books with others through points. Users gain points when they give books to others.
Booksalescout.com – Online community of users allowing them to sell books in the US.
Bookswim.com – Book borrowing service with free shipping for registered website.
ConnectViaBooks – A social networking site connecting book lovers and enabling them to discover other similar interests.
GoodReads – GoodReads is a book reader’s community enabling members to review, share books they have been reading.
PaperBackSwap.com – Users can share books amongst each other and only pay for the delivery charges.
Pazap.com – A book trade engine for students to buy and sell old books.
Read It Swap It – A free service that allows users to exchange books with others.
Revish – Revish is another community for book lovers, letting them review their favorite books, group up, or simply tell the world what they’re currently reading.
Shelfari – Shelfari is a popular social networking service for book lovers.
Socialbib – Book swapping network between students.
Business Networking & Professionals:AdvisorGarage – It is an online directory of advisers who are willing to assist budding entrepreneurs.
ArtBreak – ArtBreak is an artist community for sharing and selling artwork.
Blogtronix – Blogtronix promotes corporate social networking, enterprise 2.0 and wikis.
Commutal – Commutal is an online sharing platform for businesses to create media rooms, participate in domestic groups and share event happenings with each other.
CompanyLoop – An online co-working community for global businesses.
ConnectBeam – Connectbeam offers social networking specially designed for corporate users.
Decorati – An interior designer community enabling users to post items for sale and for exchange.
DoMyStuff – A good site for working professionals looking to find online assistants.
Doostang – An invite only career community for professionals.
Fast Pitch – It is a quickly growing business networking community in corporate world. Its online provides users with a one-stop shop network to market their business.
iKarma Inc. – iKarma is a specialist in providing customer feedback for organizations and professionals.
ImageKind – ImageKind is a community and marketplace for professional artists.
Jambo – Jambo lets you connect with your neighborhood friends.
Jigsaw – An online business card networking directory for users to establish contacts with each other. Each business card is listed with an email id and a contact number.
Konnects – Konnects enables members to create their own professional networking communities.
Lawyrs – A professional social networking community for lawyers.
Linkedin – LinkedIn is a professional social networking website for business users, one of the most popular such sites out there. Some aspects of it are free, but many are paid.
mediabistro.com – mediabistro.com is for professionals in content or creative industry.
Pairup.com – Pairup connects business travelers assisting them to travel together.
Ryze.com – A site for establishing new connections and growing networks. Connections for jobs, building career and making sales.
Spoke.com – Spoke offers access to business network of over 40 million people worldwide.
Visible Path – Visible Path helps organizations to integrate social networking into their existing tools.
WebCrossing Neighbors – It provides a private label social network with personal spaces and user groups.
XING – XING is a networking directory of business contacts powering relationships between business professionals allowing users to connect with each other.