If you have family members who still rely upon a landline and screen their calls using the message machine (Hello, Mom and Dad!), a Ringboxx from Home Phone Tunes is in order.
A Ringboxx lets users program specific ringtones for individual callers on their landline phone--just like on your mobile phone. They'll purchase tunes from the Home Phone Tunes Ringtone Store and know instantly who's calling without caller ID.
This technology would have been key about ten years ago, but better late than never, I suppose.