I'm curious to hear other's thoughts on they think would be useful.
Please don't hold back ideas! There's very little harm positing silly or unlikely ideas, but there is some potential value (perhaps more than you realize).
Inspired in part by calebo's comment here
Related: Some "Top Charity Ideas" by Charity Entrepreneurship: https://forum.effectivealtruism.org/posts/ykwQCpBxL3qPKAAqx/top-charity-ideas-2019-charity-entrepreneurship
An old LessWrong thread on startup ideas: https://www.lesswrong.com/posts/YbCc3NRrr5avvWSHT/who-wants-to-start-an-important-startup
There's also this post plus comments.