I've done a column on a poor man's load balancer. If you can run a light web server on each of the machines in question, that'd be a simple way. If not, you can run a custom HTTP::Daemon server on each machine to do roughtly the same thing, or even a SOAP::Lite server.

Or, there might be a broadcast protocol already enabled. BSD has the ruptime protocol: maybe Linux has the same.

-- Randal L. Schwartz, Perl hacker