A few more that I've come up with. I find that the themes of inconveniencing the PCs and putting their privacy and secrecy at stake are the threat ideas that come to mind most easily for me.
It's For Your Own Good
Outline:
Due to one of the players recent erratic behavior, poor academic performance or some other suitably Monsterheartsey themed complication one of the characters has been assigned a social worker. DSSHS will be preforming random drop by inspections and interviews of the players family and home environment. Along with scheduled therapy sessions downtown at the courthouse or some other suitably authoritative location.
Stakes:
A concerned Big Brother is watching and keeping a careful eye on the player. Perhaps smoothing over small complications but ready to move in and make life miserable if major complications arise ( perhaps Community Service). What if they find out your secret? What will you do then?
Threats:
The PC's assigned social worker
The local Judge, police, sheriff
Non-in the know PC friends that may tip off or reveal too much
School Teachers, Family anyone looking out for their best interest
The Mayor Hereby Welcomes Omni Corp.
Outline: A major construction firm/corporation /big business has decided to move into town and make it their central base of operations. To do this old run down sections of town or tracts of unused land are being bought as a site for future construction.
Stakes:
A new major player is in town now. Snooping around trying to get a feel of the place, buying up peoples homes, farms, abandoned buildings etc. The same types of places that monsters like to skulk and get away form humanity. Perhaps where their past victims lay buried. Either way it might be best to lay low for a while.
Threats:
Various corporate drones looking to exploit the situation
Construction crews uncovering secrets/bodies, destroying ghosts houses
Town authorities that want to encourage the financial boom this will bring
Martial Law
Outline: One afternoon an announcement goes out over all the local stations. Martial law has been declared by the military due to a chemical spill or some other nebulous reason, A curfew will be in place and patrols will be out to enforce it.
Stakes:
Is the military telling the truth? Or do they know something more? Perhaps they have evidence of supernatural occurrences and want to apprehend the suspects. Now they have all their potential suspects in one place with no way out. Will the PCs be captured? Will they have to turn over someone to the authorities? Can they escape?
Threats:
Military forces, soldiers, officers, the general whose pet project this is/ Maybe even a Congressmen/MP
Other supernaturals that may be working with the military. Or just give away their presence
Supernaturals who may know about the PCs who might let information slip
I Want To Be Leader
Outline: A local Cult/Coven/Supernatural organization is undergoing what amounts to a civil war. With rival sides vying for control of the organization. Drawing the PCs into a messy tangle of loyalties and betrayal.
Stakes:
Who will the PCs trust? Who can they trust? What do they want form than and why? Will they back the right side or earn enemies. Sometimes staying neutral just serves to ensure you have enemies on both sides. Either way they must choose and choose quickly before things go to hell in a handbasket.
Threats:
Both sides of the organization
Others moving in to take advantage of the chaos
The New Messiah
Outline: A rather wacko religious cult has become aware of one or more of the PC's existence. They now consider the PC to be their new messiah. Congratulatons! You now have lackeys. The bad news is they are overprotective and possessive of you to the Nth degree.
Stakes: Will the PC bask in the adoration of their new found cult? Or will they rapidly tire of the attention. Will it alienate them from their friends, family? How will the “true believers” react if the PC denounces them/ goes Darkest Self/tries to slip away?
Threats:
The ATF or some other government organization that keeps track of such things
The PC's family and friends who may not agree with them or the Cult
The Cult members who may be more than a bit unhinged