Wake on Lan and several computers

Is there a way to send a wake on lan packet to every compuer on the
network WITHOUT knowing the mac address of each? All of the computers
support WOL in the BIOS and theya re all on the same network. I just
don't want to have to find out every address, unless there is a way to
script it so it looks for all of the MAC addresses of the computers on
the network and sends the wake up packet to every system on the
netowrk.

Thanks

REB