I managed to get my junk mail down to practically nothing by using those postage-free return envelopes to tell them to take me off their mailing lists. They have to pay postage for those on their end (even though it's a reduced amount) and they started taking me off their lists in a hurry!
For what it's worth, I live in northeastern Arizona and the information to use for filing 2003 taxes on line was in my mailbox on January 2nd! (They didn't waste any time, did they?)