You could have different themes for your scrapping event. Have a Heritage night where people bring in old photos to scrap. Have examples of different ways to scrap the old black and white or sepia photos. Show different ways to scrap family trees. Give a prize the person who has the best old dress on.
A vacation night where everyone dresses in different vacation attire and scraps their vacation photos.
Demonstrations on how to scrap photos taken at church events and everyone can dress for church. Print off a few prayers that are common in your church for journaling squares or copy a few songs from the song book.
Of course than you have Holidays which are easy to come up with ideas. Halloween, everyone scraps with Halloween colors. Do Christmas in July just for fun.
You could have a "tool" night. Everyone brings in their favorite tool and does a short demonstration. Be sure to wear a tool belt.
Swap night. Everyone brings in a page to swap. Draw numbers to see who gets which page.
Leftover night. Everyone brings in their scraps and/or unwanted scrapping material to go on a table for the others to take what they can use.
You could ask different scrapbooking consultants to come in to do a demo on their brand of scrapbooking supplies. Just tell them it's for a demo and not for selling that night. It still is to their benefit to get there name out to more people.
Have a Hat contest. Everyone makes a hat from scrapbooking supplies only. During the crop they can vote on the best one.
Photo day, Have someone come in to take individual portrait shots of everyone. Good idea around Mother's day. Everyone should have a great photo of themselves done at least once a year so we can scrap ourselves once in a while.
Have a 'Book of Me' scrapping day.
Make a recipe book day. Bring in their recipe and bring the recipe made to share.
I Scrap! Take a photo of each person scrapbooking so they can make a page of them scrapping. I did this for one year. I took a photo at each scrapping event, scrapped them and it's one of my favorite albums. I know not everyone would want a whole album but at least they should have one page of them scrapping.