Ever been copied - what would you do.

Ever had someone register a URL with the same company name as yours in a different country, and set up pretty much the same thing as you?

So you are acmebidding.com and sell stamps
and they are acmebidding.othercountry and sell stamps very similarly!

I guess copyright means nothing as you cannot copyright a name of a business or a website name, and Tm s are useless unless you have one that covers the territory and is exact.

Any ideas?