I've never deducted that type of thing; for me, the benefit is having all that extra stuff out of the house. The exception was when I gave a piano to the church; I got an independent valuation of it and a letter from the music director at the church confirming the gift.
I have cancelled cheques for everything else.
I like clearing out the house, and the deduction. :)
Hey, if they give me the opportunity to lower taxes on my own, I'm taking it!
All the activism in he world will likely not lower my taxes any more than I can do by cleaning house, and helping someone less fortunate at the same time.