Maybe this isn't news, and I'm the last person to notice this, but after seeing James Wyatt mention that Siri can roll dice, I gave it a try. You can ask Siri to roll a d4, d6, d8, d10, d12, or d20 by voice, natively in iOS with no dice-rolling app required. Siri even reads the result to you. Sadly, I couldn't get Siri to understand "3d6" or "3d10" or any other multiple. Anyhow, this is news to me; I don't know if it's common knowledge to the rest of the world!