If it are your sites, change them, so they behave as you want.
If it are sites owned by someone else, they probably they use your IP-address to determine what to show. The solution then: find a USA or UK based proxy. I don't have any experience with them, but googling PUBLIC PROXY might be a good start.
Kees
I bought a new MacBook and registered it with the US in system preferences. I am physically in Budapest, Hungary. All my sites come up in Hungarian in spite of the registration preference. How to change it? I would like to access iTunes in dollars, not euros!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic