Self assembling robots. A team of researchers at Harvard has figured out how to get a swarm of 1024 tiny robots to work together and self-assemble into complex two dimensional shapes without anyone interfering.
Simple RC car for beginners (Android control over Bluetooth)
arduino car http://www.pinterest.com/luciobrit/arduino-raspberry-pi-galileo-other-boards/?utm_campaign=recs_141103&utm_term=3&utm_content=551479985559376966&e_t=b540d3f28ea448ddb9e3b793e6fa5963&utm_source=31&e_t_s=boards&utm_medium=2011
"Micro Aerial Vehicles" ( no larger than a common house fly) - Robot insect spies are in military use www.SELLaBIZ.gr ΠΩΛΗΣΕΙΣ ΕΠΙΧΕΙΡΗΣΕΩΝ ΔΩΡΕΑΝ ΑΓΓΕΛΙΕΣ ΠΩΛΗΣΗΣ ΕΠΙΧΕΙΡΗΣΗΣ BUSINESS FOR SALE FREE OF CHARGE PUBLICATION