As a Brit who lived in Germany for a while, a lot of Brits and Germans will fill each other's glasses before their own when sharing wine or water. Can't say anything about Americans though.
When I'm out with friends and we order a larger bottle of beer (like chimay) or get a pitcher the person who grabs the pitcher usually pours for others before themselves. It's pretty informal though, other times we just pass the pitcher around and wait for everyone to get their drink before starting. I'm in the southeast, not sure what the manners are like for the rest of the country.
I'm Norwegian and have lived in London for 15 years now, and I can't say I've ever noticed Brits pouring their own glass before others. I think I'd have noticed, as I would have found it quite rude if people served themselves first.