Using a slug as a client to wake other computer on the LAN.
# ipkg list | grep -i wake perl-wakeonlan - 0.41-1 - A Perl script that sends 'magic packets' to wake-on-LAN enabled ethernet adapters and motherboards, in order to switch on remot wakelan - 1.1-2 - send the magic wakeup package over the LAN
or a Python script http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/358449
There are PHP script as well. Feel free to add link here.
If you want to get fancy, once you get the command line script working, you can install a small web server, invoke the script from a CGI script. You can even add security, then forward port so you can invoke it from the internet. See http://www.nslu2-linux.org/wiki/Optware/Haserl for example.
There might also be PHP version of wake-on-lan script available.