I'd like to see an RSS item-level recommendation / discovery algorithm driven by recommendations made by a cohort of people who have similar likes to me. I wish there was a standards-based to publish a stream of my "likes" from my feed reader, and to "consume" the "likes" of others. When I add somebody's blog to my feed reader I'd expect it to pick up their "likes" (much like how people used to have a "blog roll" on their own site) and begin to consume the "feeds" from the sites they "like". It reminds me a bit of PHP's "web of trust".

Hacker News, arguably, functions in this capacity for me now. The cohort is the entire population (since we all see the same item rankings), though.