Something

function array_sort_bykey(&$arr, $key)
{
	$order = 1; // -1 = Ascending, 1 = Descending
	$sortby = "['".$key."']";
	$mysort = create_function('$a,$b', "\$a1=\$a$sortby;\$b1=\$b$sortby; if (\$a1==\$b1) return 0; else return (\$a1<\$b1) ? $order : 0- $order;");
	uasort($arr, $mysort);
}