This is an interesting idea. I've never heard of something like that, but I could see a market for it.

I know of a couple alternatives which do exist:

1) Get a telephone which does distinctive-rings for different callerID classes. You can put people you WANT to hear from into a certain list, people you DON'T want to hear from in another list, and unknowns in a third list. Then the phone will ring with different types of tones depending on which list the number falls into.

2) Get a cordless phone with CallerID on the handset. Then have the cordless with you while watching TV.