Importing documents

I'm wondering if there is a standard DOM functionality that can read a 
file, preferably with the ability tucked in to use both 'get' and 'post' 
methods of passing form data. Something in the style of 
"ActiveXObject('Microsoft.XMLHTTP')" in IE or "XMLHttpRequest()" in Mozilla 
(Two functions that by the way heavily resembles each other), or even just 
something that takes a URL and returns the content as a string or even 
better an object which through DOM methods can be inserted into the current 
document.

// Liorean