Such a thing is really not needed ... but ... I have found myself a time or three without dice or wanting something to speed the process up a little.
Rather than rolling 4 times for 3d4 and add +5 ... would be nice to be able just push a button and roll them all. I must admit as a young-ster seeing the plastic dance was an amusement.
This one seems to to be the one of choice for on-line:
And here's a list of top ten but who knows on such things:
Just polling the troops to see if such a thing exists.