The best way to send reminders to others and track them is to simply send them via email, in person, or by phone and then jot them down on your own waiting for list that you review every week. Make sure to jot the last time you took action following it up with them so you know when to check in again.

This is what I did when I designed my own setup for delegating things to others. I have a button that says "Delegate To", I click this button, and it sends an email with a special tag "> Waiting For" at the end of that subject line. Once I've sent the email it automatically puts the item in my waiting for folder on my computer desktop with a note that I'm waiting for this person and that I sent them an email on the appropriate date. If the person emails me back, it grabs that waiting for item, changes it to @FollowUp: <> just got back to you, what's the next action to move this forward? and puts this in my Actionable folder on the desktop. So far it's working well for me and I think the same philosophy can be applied to different paper and digital implementations.

Hope that helps.