As a rule, I'm pretty suspicious of any pop culture entry with the word "party" in the title. Typically, if something has to sell itself as a party, it's probably not.
Still, the good folks over at IGN report the WiiWare download Ghost Mansion Party is a pretty fun Halloween-themed shindig that continues to please after the 31st. Inspired by Nintendo's Mario Party game board design, Ghost Mansion is unique in that all four characters travel together in a part-cooperative, part-competitive gameplay experience. The game packs a lot into each set piece, with a lot to actively take part in instead of just looking at. Also, the chance to either work as a team - until it's every man for himself, or until you just decide to eff other's up - makes it a fun ride.
Visit IGN for the full review.