Also, being able to combine rss with custom filters mentionned in other comments would be a killer feature - in order to be able to get all of one interest from the world most active tech feed.

Yes, it begins to be difficult feature requests, sorry about that :)

If I remember correctly, an article needs to get some number of upvotes to make it to the RSS feed. For those who don't have the time to read every single article on HN, this is a useful filter.