Traffic circles! Harlow's collection, as Kevin has remarked, is legendary.

French "circles de traffique" work similarly, but only seem to allow for one circulating lane of traffique, and insist that "vous n'avez pas le priorite". And they go round widdershins! The rationale for UK driving on the left is obviously so that WE go round clockwise!

There is only one roundabout in the Frankfurt area in Germany, at Rodgau, and it causes untold confusion and numerous accidents among the otherwise orderly Teutons. They even have special coffins for the victims with gold decoration to commemorate the Teuton car man. ;o)

Alternatively, we could do away with roundabouts (I think I actually prefer "traffic circles"!) and adopt the South African convention, whereby the first vehicle arriving at a crossroads has the right of way. This can require a fine judgement and leads to some interesting encounters, but keeps the body shops (of both kinds) in business.

On the subject of dangerous conventions, how about the legal right turn against a red traffic light, as in the US?

No, we're going to have to learn to live with smaller vehicles or no vehicles at all, but this can't be done until public transport and the rest of the infrastructure has been sorted out.