I had an old piano which I thought would be easy to sell. In the end I gave it away to a charity. If the piano is particularly heavy (as mine was) make sure the people coming to collect it have the right equipment for moving it otherwise they'll scratch your floor to bits.
It was a local charity that recycle household goods. Have a look in the yellow pages for furniture recycling, or contact your local council. Some don't take pianos but they may be able to point you to someone who does.
I agree with FreeCycle. They're fantastic! And it serves our communities well.
We need a piano in our children's home in Moldova. But the challenge has been with transport... I probably would have jumped at the chance...had I had the right form of transport.
We had an old, fairly good condition, and couldn't give it away and believe me we tried hard to find anyone who wanted it, In the end we had no choice but to break it up to get rid, which didn't feel good! Try and old Town Hall or ask at your local church.