Shammstein, at P.A.'s on FridayHalloween weekend is
the only time of year during which you can choose between two -- yes,
two -- Poison cover shows. Check out the local rock fare this weekend
as Boston bands strap on their best imitation gear and pay homage to
the greats in venues across the city, from The Talking Heads to Black
Sabbath to Rammstein and back again.