Sometimes I love the times I live in:

Scenario
1. A co-worker has temporarily lost his hearing
2. He has surgery scheduled to fix the problem. 
Problem: what does he do to hear between now and getting it fixed?
Solution: He has his smartphone rigged up as a hearing aid.

It's not perfect, and certainly wouldn't replace a proper hearing aid (fitted and tuned) but as a stop-gap measure... pure awesome.