Terrific question. Halloween is a great time to give back, help your community, and yes, in doing so.. improve your resume. A great website for you to check out is: DoSomething.org/search/apachesolr_search/halloween. From there, pick a campaign whose cause is something you can really get behind. If you volunteer doing something you feel passionate about it will A) be more of a fun experience, as opposed to something you feel like you "should" or "have" to do B) you'll be more inclined to continue volunteering for that cause which looks much better on your resume.
An additional idea: Volunteer at a local children's hospital (especially if you like kids!). There are hundreds of kids confined to hospital beds while they wish they could be dressing up and roaming their neighborhood streets with their friends and families. Simply spend time with them. Bring Halloween to them. You can carve pumpkins, and bring some face paints and a whole bunch of candy to give them a trick-or-treating experience they'll never forget:)
As far as your resume goes? You should always have a section detailing your extra curricular activities (it's common to title it "Activities" on your resume). Once you volunteer (again, I recommend volunteering routinely - the longer, more consistently you volunteer the better it looks on your resume) you can add it to your resume. Include the name of the organization you volunteered at or campaign you started or were a part of, explain what you did and what came out of it, and the date(s).
Hope this helps!!
p.s. - I thought this question was so great I wrote a blog post about it! Check it out>>👻🎃 "How To Turn Halloween Into A Huge Boost On Your Resume"