Window Spawner - opens windows, over and over and over again. Sucking up memory resources, until Netscape uses all of it's assigned memory and crashes
Continous Reloads - Reload the page every milli-second
Empty While Loop - Just sits forever in the while loop
Memory-Monster - infinite calcultations can take up a lot of memory ;P
mailto submit bug - putting a '+' in front of the email address in front of mailto in the action of a form is BAD!