Not my idea, but just read a great editorial by Zac Bissionnette - All those big banks that are living off taxpayer's dime (including their bailout bonuses) send out probably hundreds of thousands of credit card offers with those handy and helpful SASE's for your thoughtful return of the application, paperwork, etc.
So, why not remove any reference to you (name, postal code, etc.,) and just mail the blank paperwork back to the bank - The USPS needs the money and big banks need a little more motivation to do the right thing.
Upon personal reflection, wouldn't this work for most junk mail offers that include a SASE? Again, caution with making certain all personal references are removed. My thought would just be a blank piece of paper with smiley face stickers or some such nonsense.
Well, they are the ones that asked - I have a right to respond, don't I??? And so, I think, do you!