My ever-vigilant spouse, however, discovered this in her never-ending quest to map the ends of the Internets:
Granted, it only draws one line at a time (which isn't much of a bike lane), but I can easily imagine bodges that would leave multiple chalk trails -- think of that thing your grade-school music teacher used to draw the five lines of a musical staff on the board. Rig a chalk line to each side of the bike, and you've got a semi-permanent bike lane (at least until the next rainstorm washes it away). Or you could stick with one line, laid down by a group ride leader to let the rest of the ride know the route.
I'm sure there are laws against drawing lanes (albeit temporarily) on public roads, but it's still fun to think about. If nothing else, this could heal some of the emotional scars inflicted upon yours truly by multiple art teachers over the years. With traditional art tools, I can barely draw flies -- but with a bicycle, who knows?