You can use the POST method.
Php does make life easy by grabbing anything out of the query string of a url simply by asking for it by name. This works great with a GET. Here's something that you can do to get vars through a POST:
$someVar = $HTTP_POST_VARS[someFormElementName];
This will get the what you need from a POST method.
This can be really cool if you want to load say a bunch of checkbox items into an array. Simply name all your checkboxes something like: myCheckbox[] - then on the resulting page doing this:
$myArray = $HTTP_POST_VARS[myCheckbox];
$n=0;
while ($n < count($myArray)) {
echo $myArray[$n]."<br>";
++$n;
}