generates better randomness

test.php

<?php

function generateRandomness( $fraction = 0.025 ) {
    return - ( log( 1.0 - (float) ( mt_rand() / ( mt_getrandmax() + 1 ) ) ) / $fraction );
}

for( $x=0; $x<=10; $x++ ) {
    $rands = 100000;
    for( $i=0; $i<=$rands; $i++ )
        $rand += generateRandomness( 1/40 );
    echo( $x . ': ' . ( $rand / $rands ) . "\n" );
    $rand = 0;
}