This genre of page remains one of perrenial fascinations. The ideas may not always be of the best quality, but they tell you more than you’d expect about the writer’s quality of thinking, and what their circle of competence looks like.
If you don’t have your own Ideas page, I suggest trying to make one. It’s fun.
From Justin Duke, software-related product ideas with reasonable scope.
Novel possibilities for digital interfaces.
Around 500 or so odd links/
List of ideas for better web browsing, from Tyler Angert.
List of innovations which, if successful, will dramatically improve our society, from (Harsimony]
Short list from Mathurah
From Carolyn Zhang
I’m not sure if Gwern is being completely serious here, but these do seem fun.
Concepts I can’t raise, but I think should exist. (Anson Yu)