I came across a very sad article in The Guardian today entitled "Bicycle graveyards: why do so many bikes end up underwater?". It talked about the predilection some people have for throwing things into water - in this case bicycles.
Most of my favorite routes go alongside water - rivers, streams, oceans. I wonder how many abandoned bicycles, that started off as prized possessions, are hidden under those waters. It's like buying a puppy, watching it grow up, and when it gets sick, abandoning it.
There are so many things you can do with an old bike other than tossing it and mucking up the environment. I've donated many bikes to charity, friends, scouts, etc. There's a few bikes in my garage right now that could use a new home. Someone would love them.
Just down the road from where I work there's a place called the Loma Linda Bicycle Hospital. I love that name. It's just a guy who takes in old bikes, fixes them up, and gives them away to people who need a free bike. He also offers bicycle maintenance advice and training. His whole ethic is to keep bicycles useful and loved for as long as possible. I need to go buy him a beer.