Having recently dealt with mice, I found that a little device you plug into a wall socket that emits a tone that mice can hear and it drives them out of the walls (doesn't effect pets). It really seems to do the trick. I know it's not Perl-related but it is techy/geeky (electronic device) and it appears to be effective (haven't seen more mice since it was put in). Our two dogs and cat haven't indicated any more mice either :-)