I use Alexa. It has customizable reminders; it reminds me to take my medication, then a few minutes later, asks if I'm quite sure that I have done so. It interfaces with my Google Calendar, can place a call to my mate on her cell phone, has customizable 'to-do' lists, a 'memo' function, and a timer that helps with time management (like obsessive Internet use). If outside noise is making me feel overstimulated, it can play white noise (like 'rain sounds') or nonverbal music (I like 'Liquid Mind'), which helps me tremendously.
I'd recommend it to anyone with cognitive/memory/executive function issues.