Um móvel, com ímãs, para montar de várias formas/ A furniture, with magnets on the sides, that allows the assembly in different formats
Create a newscast based entirely on a community's tweets, status updates, RSS feeds, and other shareable links.
Create an Artificially intelligent teaching application that tutors students remotely using open source technologies...
Public transport for free. Paid by sponsoring or taxes => extremly good for nature & would make taking the train/bus hip again
Some people write diagonally. A notebook for them could be fun.
Parkings around the downtown of Belo Horizonte with public bikes to access the busiest area of the city reducing the traffic jam.
Add two existing technologies. Write and draw directly on the surface of a table is better than on the surface of a tablet.