I cannot get the rewrite rule correct...

This is what I want:

I want both of the following:

http://www.site.com/folder/file.php?foo=bar
http://folder.site.com/file.php?foo=bar

To change to:

http://www.site.com/file.php?foo=bar&var=folder

Everything I try I just cannot get the original variables to pass...

You can do this using the ForceType method or mod_rewrite. mod_rewrite is a little more complex, but more powerful. Visit this link:
http://httpd.apache.org/docs/mod/mod_rewrite.html
hope it will help :)

RewriteRule ^(.*)/file.php?foo=(.*) file.php?foo=$2&var=$1

should work for the first, unless there's a subdomain created for the second, i don't think you'll be able to do that.

I need the actual variable names and the variable's value to be passed along. Oh and file.php maynot always be file.php. Those are the main reasons I'm having such big problems iwth it.