Time-based sub-branding
If your venue changes its branding certain days of the week, you can add a recurring event with the right branding.
Sponsorships and promotions
Promote a specific product on a given day by adding it as a photo watermark, or by changing the default hashtags for the picture.
One-off parties
Offer your guests to have their own branding in the photos, e.g. for a birthday event or bachelorette party.