Mine GO BOOM has incorporated a script that I wrote back in 2005 using PHP which would take a *.lvl file and convert it into a PNG. You can see it in action over at the URL:
http://forums.minegoboom.com/viewtopic.php?p=69142
The original PHP script posting was located at:
http://forums.minegoboom.com/viewtopic.php?t=4540