Creating an international section, best way?

Hi all,

I'm looking to expand my website to have some international customisation. That is, there's a primary url www.domain.com that is internationally themed, but I'd like to have www.domain.com.au and www.domain.co.uk to provide the same content but fine tuned to the respective country.

My question is, what is the best way to go about it? I'm keeping in mind here that content will be 80% the same. I see my options as;

* Have www.domain.com.au with seperate hosting.
* Have the .com.au redivert to www.domain.com/au
* Have the .com.au redivert to au.domain.com

Any thoughts or suggestions?

Cheers, Daniel