Interestingly, while Russia drives on the right (with the cars' steering wheels, of course, on the left), many cars in Siberia and the Russian Far East are left-side vehicles (with their steering wheels on the right) because they are second-hand imports from Japan. Makes for some scary driving...
QANTASforever, I found some info regarding your question at http://www.amphicars.com/acleft.htm
"Britain's imperial expansion (all of the pink bits on old maps) spread the keep left rule far and wide. This included India, Australasia and much of Africa (Although many African countries changed to the right later when they became independent).
"France also had quite an empire after the revolutionary wars and the keep right rule spread through much of modern day Europe and to colonies such as Egypt. The connection with the USA is thought to be General Lafayette who recommended a keep right rule as part of the help that he gave the Americans in the build up to the war of Independence. The first reference to keep right in USA law is in a rule covering the Lancaster to Philadelphia turnpike in 1792."
"Believe it or not, its easier for the majority (who are right handed) to drive in a right hand drive car, because when changing gear..."
Fortunately, most cars here in the US have automatic transmission, so this isn't an issue for the majority here.
[Edited 2003-02-09 07:03:22]