On the same line of thinking as: Notify Author when Question is migrated I think it would be helpful for users whose answer were either accepted, or awarded a bounty (maybe even over a certain number of votes) to receive a notification that the question has been migrated.
Some users will spend a fair amount of time researching an answer and going back to edit as new information becomes available. It seems only fair to be able to see where this time has ended up.
I recently noticed a 400 rep drop and assumed the question was deleted and the information I posted lost. After asking in meta ( I've lost a lot of rep when the question with my answer has disappeared ) I discovered it was simply migrated and I had no way of knowing.
Please notify users who had an accepted answer or were awarded a bounty if the question was migrated.