What would you need an invitation for?

I'm a new stay at home mom and made an etsy shop for downloadable invitation templates. I have a few baby shower and working on some for weddings, but so far the only sales I've gotten are for military going away parties.

I'm assuming there aren't many for that occasion, which is why they've been popular from my shop. Any ideas on other occasions that may be hard to find things for? I know there are a lot for weddings so I would like to focus on other events. Any ideas are appreciated!