Most any Cisco router will do the trick, but the oldest you'd probably
want to use for something like this would be a 2500 series. They can be
had all day long for $10-20/ea, they pull very little power, and their
software is...erm, "available" if you know what I mean.
Just picked up a Catalyst 4948 (probably a bit overkill, but it was free)... not sure if I
have the correct licenses... in any case, if anyone has a quick bit on setting this up, I,
for one, would be interested...