Right now you can do the Halloween quests for the Pumpkin brothers in Wizard City. With it also means the holiday drops from certain bosses, the Halloween Spires (the three towers) and the return of Baron Mordecai. So make sure to stop around and have some fun!
To go along with this, Mercs4Hire is doing a bunch of weekend runs. Check it out over here.
Going to these is a great opportunity to try for the awesome Halloween loot. They also have a bunch of contests that will be going on for cool stuff too. (those are all here)
Hopefully you can have some fun with these things this month. I know I can't wait.
Though, it would be cool if they would have a new event of sorts come out for the bigger holiday celebrations every couple years or so. Repeats are never quite as fun. :\
Your very distracted host,
- M. Trollfriend