I've been working on a little website to pull out links from the comments on the "Ask HN" page. Often there is some great advice in there, and it seemed in the spirit of Hacker News to automate that.
It would be nice to be able to provide a link to an older post and get the links.
Stats, such as top sites included across posts (all-time, this year, etc.), or posts with most links.
An example - I posted a question about non standard keyboard/mouse setups for coding. There were a lot of product mentions in there and what people are doing with them. Not a lot of links though so it would take some text processing.