You're not allowed to request things on this site, but I'm pretty sure there is a free Halloween set at the Sims 3 Store.
Right you are
A Pumpkin Lamp (Jack O' Floor Lamp), Ghost Lanterns, a Black Cat,
a Ghost Mirror, a creepy Chandelier,
and a Dark Midnight End Table.
Had them up for a while now, and seems like nothing is happening,
though the store said for example:
Clark's Pack of Ghosts
These pack of four wall shades have been cut to represent the ghostly nature of Halloween. Don't turn your back on them too long for they may actually turn into ghosts!
my Sims don't even get the creeps around that stuff....
"It is not that you will go mad.
It is that you will beg for madness." - Volrath