Dreaming up bike gadgets is something of a boom industry these days. From somewhere called Studio Gelardi comes an idea called Contrail, the velo equivalent of a fox's territorial marking. A chalk dispenser attached to your bike (right) leaves a temporary trail on the road.
It confirms the presence of cyclists to other road users. As we know, cyclists are invisible until one of them jumps a red light.
And with patience, and a Nazca plain of road space, there's the possibility of tracing out a rude message to the bus that's just cut you up on Waterloo Bridge.
It follows the ingenious portable laser bike lane announced a month or two ago (right). An organisation called Altitude claims to be showing this off in October 2009, but so far it only seems to exist in blog comments. Nice idea, but it only works at night on dark streets.
If this sort of laser-beam technology proves workable in daylight, it could be made genuinely useful. How about projecting an arrow on the road surface in front of your bike, to show you what route to take? Then your GPS-based route planner could keep directing you the most efficient way.