How does one dispose of a bowling balls that can no longer be used?  Just in your normal garbage? If so, i don't feel comfortable doing that.  Lol.  I have like 6 balls cracked all the way around the ball. 

I put mine out in the yard

We usually just toss them in the regular trash.  One per week if we have more than one.  Also threw one away in a trash can at the bowling center one time [I hated the ball so much I couldn't wait to dispose of it...after two drillings and multiple surface changes it never gave me the reaction I wanted]

Have a few beers and ride around in the country throwing them at mail boxes. 

Here people leave their old balls at one of the bowling alleys.
One of the 2 here in my hometown gets the most used balls. The other has a few too, but not as many as the other one.
I've left one Slingshot there.
I might leave the Sinister there too. I've gotten new grips on the balls I use, and the Sinister is one pound lighter than those 3 too. I was thinking I could keep the ball in case some young guys want to be a member of the club I'm in, but since I don't like the Sinister, I don't feel that it's right to give it to someone else like that. Though if they were to sand it, then it might hook like it should again.

Honestly
.. eBay.

Most of the time it would be less hassle and cheaper just to throw in the trash.

I've been donating used balls to the local high school teams as of late through my PSO.  She plugs/resurfaces them and then it helps grow the sport by allowing kids who may have a tougher time affording equipment the chance to throw newer stuff.  It's a good way to pass it on and give back.

i honesty throw mine in a bonfire in my back yard...usually leaves just the core and then ill chuck that