As for junk mail, I always got a little satsfaction by sendng junk mail back to them on their own dime. If there is one of those "Business Reply" envelopes, I just stuff some of my other junk mail into it and stick it into the mailbox for sending.

I suppose this angers somebody (he he) - but it helps the struggling Postal Service a little bit. Besides, if everyone did that, maybe the companies would find that mass mailings weren't so profitable.