There are three big problems in information access: navigation, importance (which you touch on in "authority" in your answer), and summarization. I'll talk about navigation later.
Regarding summarization:
I'd be interested in web-scale multi-document summarization and source aggregation.
The same story is repeated ten times across online newspapers and summarized on twitter in a variety of ways. Aggregate this into one headline with a link to all the articles.
Afterwards, bloggers comment on the story. It's interesting to get a summary of the different commentaries, with duplicates aggregated, and the summaries of the different commentaries dangle off the summary of the main story. etc.
