[ian0]

How about the ability for users to build and exchange "distros" of interface, information filtering and content discovery. Like themes but besides changing the layout of (a more interactive) browser it also changes how content is viewed/discovered.

Eg. the "grandad" browser with large text, football results & commentary, civic information and communications tools all lined up and easy to use. The "Kids" flavours with varying levels of helicopter parenting. And a bazillion no-JS software dev versions :P.

Perhaps even with modules. Eg. the "Im going on holidays" module displays a curated list of tools (skyscanner/wikitravel etc) to assist with that. The "Im learning to ride a motorbike" motorbike displays curated youtube content (or pre-trained models that reduce spammy search results) in addition to specialised apps to keep track of progress etc.