Stuff we've done with Free Spirits-
We play in Tir Tairngire, where they are a little more common, and also where they have the rights of citizens.
My favorite was, the PCs stopped a blood sacrifice ritual that was meant to empower a place, though they didn't know where or why. One of the PCs was a member of the Peace Force. Some more PF folks showed up, took the mages into custody, and their plane ended up getting downed by a free storm spirit. This did not make Kyle, the Peace Force PC, very happy.
Later the PCs had to go to the location that the ritual had been linked to, because they were now marked and could get in. The entrance was guarded by a barrier, and when Kyle touched it he ended up on an astral quest, in the domain of a being called the Master of Storms, and in the end he learned a word. He woke up (seconds later on the outside) he spoke the word that he thought of as an open sesame- and the spirit opened the barrier.
What he didn't know was that when he spoke the word in the metaplane to get out, I rolled a test, and he bound the free spirit. (Yes, I know that's not how it's supposed to work. I'm an evil GM, deal.) So much later, he learned that he had, as an officer of the Peace Force, bound a Free Spirit, which is against Tir law... and that if he released it, it would likely kill him... and the other PCs, who all heard the spirit's name.
So, I guess that was more "story" than "suggestion." Sorry 'bout that, but maybe someone will get an idea out of it.