With it only being a 30 minute thing I wouldn't try to do a lot or have them leave the school and have to run back in that short of time.
With it being in January and depending on what part of the country you are in you may have to consider the factor of snow. They may go to do a few quick things and be late getting back or not come back at all ( snow or no snow). I would try to get a local coffee shop and a bakery to donate a few different kinds of coffee and pasteries so the moms can just hang out and wait. You may even look into a guest speaker for that time. With it being after the new year 9 out of 10 people go on diets so maybe a fitness trainer from a local gym or your local curves work out center. I would even try to get a few free gym memberships and every one who stays for that 30 minutes gets a chance to win one. Or if you get a guest speaker I would try to get a prize taylored to what they will be talking about.
You may even get a local spa to donate you a spa day package or a beauty shop to donate a full day of beauty( hair and nails).
I'm scheduling a meeting in January to touch base on our big fundraiser in March. At the Asst Principal's request (she's in charge of the funraiser), I scheduled it the same day as our other Board for preschool is doing the same informational/planning meeting. The AP will be on their agenda from 8:45-9:15am so I said we'd meet at 9:30. There's not really anything we NEED to meet about besides the fundraiser.
I'd like to have some sort of informal, relatively unstructured, purely social event that morning...when kids are dropped off at 8:30, moms can run a quick errand, meet at a coffee shop closeby, or just stay for something fun, social, before the meeting...BUT WHAT?
I need something that will entice people to come especially since most will, undoubtedly, feel like it's going to be all info they've heard before (from the AP) - and some will be but there are one or two significant changes to the even this year so I don't want people to blow off this meeting.
Maybe it could be a morning workshop for the teachers...I could send something to teachers asking if they have things a big group of moms could do for them that morning. I don't know how enticing that is, though.