There are quite a few fun activities that are free or inexpensive that are going on to celebrate Halloween week.
Gazebo at O'Brien Park 2010
Trick or Treat on Mainstreet – 4-8 Halloween October 31 < All Ages
Halloween Spooktacular Saturday October 29th at Tailgate < Adults only
Free Trick or Treat bowling from Brunswick Zone < for parents to give out to trick or treaters
NextGen Kids and Kinetics Youth Center is sponsoring a Free Family Fall Festival and Halloween Party. Families enjoy Bounce Houses, BBQ, Cotton Candy, Trick or Treat Stations, Costume contest, games and prizes.
Saturday October 29th from 2pm – 7pm.
The last Parker Wine Walk of 2011 on Mainstreet 5-9 p.m.
Trick or Treat off the Street at the Wildlife Experience
Other Halloween fun in Douglas County CO
Night of the Living Dead Teen Night in Lone Tree CO
Castle Rock has three Halloween attractions happening this week.
Highlands Ranch
Scare on the Square Halloween Party for adults only featuring a gigantic Thriller Dance time with lessons before the dance.
If you know of some other fun Halloween things to do in the area please add them in the comments. Links are OK! 
