Tires are one of the most abundant waste products on Earth yet it's the most recyclable. I mean 100% of it can be turned into a number of useful products but the most green thing to do is repurpose it just as is. The Re-Tyre concept by Carl Menary cleans and remolds tires past their prime into unique and surprisingly comfortable seating.
via Yanko
...and they make great outdoor planters too :)
I would think though, that the smell of the rubber would get a bit overwhelming after awhile. Admittedly, I sort of like the smell but I think after sitting on one for 10 minutes I might get sick of it.
Of course, these seats would be most appropriate for automobile repair places, especially tires places, ie. Tires Plus, etc.