Computer in a Pen
Jecel Assumpcao Jr posted a proposal for a $5 workstation to NOSC (No Operand Stack Computer) mailing list.How cheap can a computer be and still be interesting to use?
In this idea the computer would be just a light pen with a wire coming out of it that would be connected to a TV set's video input or antenna.
While the original idea was to power the device using solar cells, another option is to capture the electrical noise present in any wired environment and use that as the power source.
The wire would also function as an RF antenna so the device would form a wireless mesh network with its neighbors. If groups of users want to communicate but there is too large a gap between them, a possible solution is to buy an extra device (only $5, after all) and just put it in a tree or lamp post half way between the two closest houses.
The light pen can´t detect the tracking spot when pointed at a black area of the TV screen, so dark backgrounds should be avoided. The user interface would be exactly that of a Tablet computer.
Unfortunately, light pens are known to be uncomfortable to use for too long. Another problem is that parents would object to have their children sitting so close to the TV screen and would blame any eye problems (and obviously a percentage of the users will have eye problems in any case) on this.