have you ever shifted the chain into the space between the largest cog and the spokes by accident? That will chew up spokes and most of the damaged ones will eventually fail.
I saw the title of the post and thought someone was talking about me. On Sunday, I was screwing around with my rear derailleur and evidently had it tensioned too high, because as I was testing the range of gears on Forbes Avenue right by Hillman Library, the chain went into that deathtrap area, got real sticky, then froze up, and I skidded to a (panicky) stop. I'm amazed that I didn't fall over, or get run over by a passing car. That would have made that catastrophic failure even worse.
In the end, I lost seven spokes in that incident, all on the drive side, and ended up getting a new wheelset.