In Indonesia, people wear wedding rings on their right ring finger. In Canada, they put it on their left ring finger.
Being an Indonesian couple in Canada, we decided to wear ours on our right hand. Chris is very adamant about "being different than everybody else". (Heck, our wedding theme was blue -- nobody in Makassar uses blue as wedding theme).
A couple I know make different arrangements every day. They might put theirs on right hand one day, and switch to left hand the next day. They make plans, though, so both of them put the rings uniformly on certain finger every day.
Personally, it doesn't make a difference for me. BUT, I did get hit by some random stranger when I wore mine on my right hand. I had to flash my ring several times before he got the clue. ^_^ So my policy now is, when I am alone, I wear it on my left hand. When both of us are going out together, it's back on my right hand.
I don't know why people put the ring on left or right hand, though. Does anyone know?