Conference badges are basically insta-e-waste too.

Not the ones from these events they are really well designed (welll... Feature wise) and offer great learning and usage opportunities.

This one has a big colour screen and a full qwerty keyboard. It's not really to be used as a badge. More as a way to get people interested in making something cool with it.

After all, hacker conferences these days are about 50% traditional security and 50% makers.