Personal recorded replies
As a cellphone is usually always with its owner at all times, not answering the ringing phone, for any reason, often causes the caller to think (s)he is being avoided. It would help greatly if I could press a button on my cellphone when it rings, and the caller could hear a message in my voice recorded on the phone - like "Sorry, I am driving right now - I'll call you back", or, "I am in a meeting. Please call later". The possibilities are endless, and the utility immense. It won't cost much either.
Reward: Two such cellphones - my wife would like one too!