Oh hell no
Just got an email from Care2 thanking me for signing up to the PETA newsletter.
They must have subscribed me when I signed a petition about the guy who shot the lion in Zimbabwe (follow the link only if you don't mind being really pissed off).
I unsubscribed as soon as I got their email. When they asked why on the form, I told them I didn't remember signing up, and I don't like to be auto-subscribed to anything and especially not PETA.