Promote your startup on a digital billboard. Out bid other people and get featured on the billboard the next day. The top 3 bidders of each day will get their product ad featured on the billboard the following day for 24 hours.
I think the biggest issue with sites like these is there is minimal incentive for a random visitor to stop by and view the "billboard".
How do you plan on addressing this to keep it interesting and worth the bids?
Workspaces
Songbox
Product Hunt
AI Renamer