Ask HN: Going to a hackathon this saturday. Any ideas relating to ecommerce?

I am going to a hackathon this week. The topic is on ecommerce, audio and video. Can anyone suggest some ideas to build something in 12 hourse. I have been trying to brainstorm since last week, but getting only creepy ideas.

Right now, my current pick is:

Scroll based recommendation learning for e-commerce. Infinite scroll based react plugin, which generates more suggestions as scroll based on the time and scroll position on current items.

Thanks