If you look at it in the right light RSS is a lot like Usenet, with RSS feeds taking the place of newsgroups and entries taking the pace of articles. And they both have similar issues of organizing, selecting, and filtering massive amounts of information.

The big difference is that decent Usenet newsreaders have much better tools for dealing with this than RSS readers seem to. At one level this isn't too surprising, since Usenet newsreaders have been around a lot longer than RSS readers. At another level it really disappoints me, because it means that authors of RSS readers are failing to learn from history.

Here's some things I wish feed readers would take from Usenet newsreaders (and soon):

• handling 'crossposts'. I read a number of aggregated RSS feeds, and some people's entries appear in several of them; I would really like to only read them once, the first time. (Atom entries and I believe RSS entries as well have what is supposed to be a globally unique identifier for the entry, so this is certainly possible.)
• 'killfiles': even in non-aggregated feeds there may be some categories of entries that you aren't interested in reading, and in multi-author blogs or aggregated feeds you may want to filter on author. (Feed software authors should make this as flexible as possible, since the feed may not have explicit category labels and you'll have to infer them from things like entry URLs.)
• don't immediately jump to the next unread entry after I finish all of the unread entries in one feed. Newsreaders get this right; when you exhaust a newsgroup, the next newsgroup is only the default choice for where you go next; you get a chance to jump around instead.
• selection filters, to prioritize messages that match various criteria (the reverse of killfiles). One obvious filter might be 'entries that link to my blog'.

In the longer term it would be nice if feed readers could thread related entries together. Unfortunately they have their work cut out for them, as RSS entries don't have the sort of relationship markers that Usenet articles do; however, they can make deductions from things like links in entries.

With threading, the feed reader can then apply selection filters to entire threads instead of just single entries. Imagine being able to see at a glance if there's a new entry related to a cross-blog discussion that you've found interesting, for example.

(None of these features are futuristic or over the top; good Usenet newsreaders have had equivalents of them for years.)