This may sound strange, but - I recently installed a new toilet and I don't have the slightest idea about what to do with the old one - do I just take it to the junkyard, or does someone recycle old toilets?
If you have A RESTORE for Habitat for Humanity in your area you can turn it over to them possibly. They resell the items to raise money for building homes. If you find one and donate it it's tax deductable!
if it is still useable, i know of two websites for you one is called www.freecycle.org click on your region and then your state/city this is a website for folks who have useable stuff, but they don't need it and don't want it to wind up in a landfill.
the other website is www.craigslist.org, again, click on the city nearest you and then go to the free section. you'd be surprised what people will take off your hands, they've turned tubs into planters, believe me, even if it isn't functional, you'll never know who may want it...maybe even a theater group or something.