Below is the list of countries for which I know the hand; all countries so far use the "usual" ring finger (the fourth finger - counting from the thumb).
Hand side by country
Spain: right, except by Catalan people who wear it on the left
India: man - right, woman - left; worn at engaugement time
Czech Republic: left
United States: left
Netherlands, Catholic people wear it left, all others right
Jewish folks: usually right
I will fill in more countries as I find out.
Winkipedia wedding rings