I created a context called People. When I have an agenda or waiting for task that is related to a person, I will tag it with an entity's or individual person's name (this is solely what I use tags for).
I've requested the addition of Agenda to the status list, but for now I am designating my waiting fors with the Waiting status and my agendas with the Hold status.
Using this method, I find it easy to look at all of my agendas and waiting fors. When I need to interface with someone, I can easily click on Tags or my People context and see anything (all agendas and waiting fors) that I might need to speak with them about, assuming I've done a good job of getting everything into Toodledo. ;)