Don't forget, in this way they could overwrite your own variables... you might want to prefix the incomming variables with something, like so:
extract($_GET, EXTR_PREFIX_ALL, 'var_');
With the above code, you would access all $GET indeces by prefixing the index with var, e.g. $var_user, $var_page, etc.
If you didn't want to do that (though I would highly recommend it), you can simplify cahva's code like so:
extract($_GET);