We know this town is filled with ghosts, historical or athletic (we are thinking of you, Mitch Williams). But come this Easter Sunday, Philadelphia has another creature of the undead to deal with: zombies. The sixth annual Philly Zombie Crawl commences tonight and lurches on throughout the day before culminating in a party for the non-living at the TLA. Participates are urged to put on their best zombie looks and to enjoy in specialty themed cocktails. By holding it on South Street, though, we here aren’t sure anyone will take notice of the crowd change.