2.4GHz parabolic mesh dishes from Chinese cookware scoops & a USB WiFi adaptor! Called "WIFRY","WOKFI" or "WOKTENNA" (12"= 300mm diam) shows 12-15dB gain (enough for a LOS range extension to 3-5km)
A remote control car that can be driven over the internet or with a laptop wirelessly from up to 500m away. It has a live-feed network camera so that it can be driven without line of sight and a horn so that you can honk at people.