Enables travellers to sell hotel bookings bought anywhere, is free for both buyers and sellers to post or view listings. Buyers who bid on a room will know if their bid has been accepted within 24 hours, and can also cancel their bids up to the point that the seller responds. The seven-month-old company takes care of transferring the name on the booking and if the front desk doesn’t accept the reservation, Hall St will refund the buyer’s money.

Arduino boards can be purchased pre-assembled or as do-it-yourself kits. Hardware design information is available for those who would like to assemble an Arduino by hand. It was estimated in mid-2011 that over 300,000 official Arduinos had been commercially produced

Athens Wireless Metropolitan Network is a grassroots wireless community, taking advantage of new, state of the art wireless technologies, to connect people and services. The network comprises 1120 backbone nodes (as of Aug, 2010) and more than 2900 client computers connect to it.

identi.ca is an open source social networking and micro-blogging service based on the pump.io software, using the Activity Streams protocol.

Twine is an open-source tool for telling interactive, nonlinear stories.

A research project and a nomadic urban laboratory to explore that complex concept called the urban commons. The project proposes a method where the commons are discussed, defined with parameters and, sometimes, represented in short videos. In addition it creates a networks of people involved on the research about urban commons to organize workshops to mapping commons on main cities around the world.

Astronomers at Las Cumbres Observatory are investigating exoplanets - planets which orbit stars other than our Sun - and you can too. Joining Agent Exoplanet you will study known exoplanets using images taken by LCOGT’s telescopes. You'll measure the brightness of a star while a planet moves between it and our viewpoint.You can examine as many images, from as many exoplanet transit events, as you like and contribute to understanding the properties of each exoplanet.

Gnutella2, often referred to as G2, is a peer-to-peer protocol developed mainly by Michael Stokes and released in 2002. While inspired by the gnutella protocol, G2 shares little of its design with the exception of its connection handshake and download mechanics.[1] It adopts an extensible binary packet format and an entirely new search algorithm.

Couchsurfing is a global community of 7 million people in more than 100,000 cities who share their life, their world, their journey. Couchsurfing connects travelers with a global network of people willing to share in profound and meaningful ways, making travel a truly social experience.

Guifi.net is a telecommunications network, is open, free and neutral because is built through a peer to peer agreement where everyone can join the network by providing his connection, and therefore, extending the network and gaining connectivity to all.