Scoubidou (pronounced scooby doo) seems to be the biggest craze since Pokemon cards. All the kids around here are busily plaiting brightly coloured plastic cords into...well, plaited plastic cords...for no reason that I can discern.
It appears to have originated in the Netherlands. See http://www.scoubidou.nl/
I rather like this scoubidou craze. It's cheap, it requires no batteries and it keeps the little blighters quiet on the buses.