you should check out
a project by james quinlan
user-submitted links to material relating to the current page.
i'd thought it'd be neat to have a little extension that allows visitors to a site to recommend other, related material. like a shittier, totally manual search engine. sometimes recommendations sourced directly from folks can be a lot better than what google can dig up.
for example, if i'm reading an article about, oh i dont know, how deep learning works at a high level, i might be reminded that daniel shiffman has some great beginner explanations of neural networks, and i might suspect that other visitors to this article would appreciate knowing about dan's neural network videos. if i want, i can add a link to his videos via the extension, and anyone else with the extension who reads the article will see that i suggested his videos as a complimentary resource to understanding neural networks and deep learning.
prs welcome!