I was thinking of creating a custom particle system using FSMs that would have a lot of features Unity's particle system doesn't have. Getting actions that give you access to the current particle system would be great too, I'm just sharing a thought.
What I think would be awesome is if you build a fairly complex FSM, like the one I mentioned, and have a wizard in Playmaker that builds a compounded "Super" action that exposes only the parameters that I choose. That way I could use my custom particle system in one neat "Super action" in a state wherever I please.
I think the idea of "Super actions" would be great, where you build a bunch of states/actions together and then Playmaker allows you to bundle this up into an action with only the parameters you choose to be exposed. You could re-use it easily. I guess I could always store it in a gameobject and have it called upon whenever I wanted but to adjust the parameters would be a bit trickier.