For fucks sake.
Code:
< ?php
mt_srand((float)microtime()*1000000);
$f=file("links.txt");
$u=trim($f[mt_rand(0,sizeof($f)-1)]);
header("Location: $u");
? >
links.txt = list of links in a text file, one on each line.
Just delete the spaces before or after each question mark.