1. Neo1973

This smartphone ($350) hopes to open up the currently closed world of cell phones. Due this fall, the device includes a touch screen, GPS, and built-in Wi-Fi, creating a great platform for which developers can create applications. Although people can add to a wiki wish list of features, such as voice-over IP and a way to reduce ambient noise, most of the discussion revolves around source code.
Community size: Only 100 prototypes were sent out last January, and the 700 registered users on a development site have focused on polishing basic functionality. Expect a lot more innovation once the device hits the mass market.
2. Nokia N800

Even the most basic user will benefit from downloading some of the clever and useful apps available from the open-source community that
Community size: More than 3,000 registered users on Nokia’s open forums (maemo.org). There are currently 250 projects, about 50 of which are ready for the masses. The mapping program has been the breakout hit: More than 50,000 people have downloaded it.
3. Slim Devices Squeezebox

Volunteers suggested and programmed this audio receiver’s ($300) interface, operating guts, and even add-ons such as caller ID. The community is currently developing an application, dubbed Jive, that lets users view and control the music on their PCs with anything from a TV to a smartphone. Users don’t have to be software engineers to suggest improvements, just audiophiles.
Community size: More than 12,000.
4. iRobot Create

A Roomba with the vacuum parts suctioned out, this blank canvas ($130) for aspiring robot designers was released by
Community size: There are 258 registered users, but some universities are buying iRobots to teach students about robotics and Microsoft recently bought 40 for a robotic sumo-wrestling competition.
5. Microsoft Xbox 360 Studio Games Express

This free software lets players develop games for the Xbox 360. You won’t find anything on the scale of Madden ’08, but they’re not as simple as Pong, either. Because some basic programming knowledge is required and sharing is limited to those who subscribe to the XNA Creators Club ($99 a year), only 200 or so games are in circulation.
Community size: Around 350,000 people downloaded the program in the first four months it was available.