Here's a useful new Gmail feature:
Unsubscribing from mailing lists and newsletters you subscribed to a while back but no longer want to receive should be just as easy. Searching through individual messages for little unsubscribe links is too big a pain —you should be able to unsubscribe with a single click.
So we just launched something that makes this all work better, both for Gmail users and big email senders. Now, when you report spam on a legitimate newsletter or mailing list, we'll help you unsubscribe. After clicking report spam, you'll see a little dialog like this: