We now have mail, private messages, expansion of conversations in mail, comment counts, custom css, comments generating mail, deletable comments and posts.

That is pretty much the most major things that were missing.

Things I can think of that are still needed.

Pings, marking mail as read, looking at previously read mail. I think that covers all the major things a link aggregator should have.

If there are any that are missing that you can think of, please let me know. I think this marks the milestone of being usable.