Another thought...The horn could learn and mediate your reactions- if you do heavy presses all the time you are likely to be an aggressive driver and the tone shifts to make you sound less angry.

Almost any horn indicates the loss of patience of the sounder. Perhaps a musical passage would convey a pleasanter mood.

Good idea, but the negative aspect is that to use the horn for many different purposes, such as "thanks", etc. might cause a good deal of noise pollution as people begin using the horn for things beyond a simple "get outta the way" or "watch out." It might not be as bit a problem on the open road as it would in major cities. Of course, such sounds might end up being softer and somehow more pleasant than a traditional horn-blast.

As an addition, a friendly "go ahead" honk would be a blessing in right-of-way situations between not only other cars, but pedestrians as well.

...and perhaps a horn that when you press it twice, lightly, gives off a 'thank you' honk in a more sarcastic tone for when someone doesn't let you in. Giving the horn a little harder squeeze, while you're slunk down in the seat could be used to honk at the cute girl walking by...a "hey-you're-cute" honk.Perhaps 3 quick taps on the horn can signal a "hurry-up-I'm-waiting-outside" honk. And a special sequence would announce to someone that they are in the left-lane and you are trying to pass them....a sort of "excuse-me-I'd-like-to-get-by" honk.ugggh....sorry Mr. Truck Driver... I didn't mean to suggest you are cute!!