Next up is comment collapsing, but that feels a bit more difficult. Livejournal, for example, has some really fancy algorithm for doing it that looks really good.
Where there is a root comment with a reply that then has a bunch of replies, the root comment and its reply are not collapsed, but all of the 3rd-level children will be collapsed.
It seems that a thread can go as much as 5 deep before it is collapsed if it is linear.
Also, collapsing is only triggered if there's N comments, where I think N is 50.
I guess I should try to wander through the livejournal code base and see if any of it makes enough sense to figure out how they do things so awesomely.
There's just one other question I have... How do I fetch only the comments I need for a page? Right now I fetch all the comments then throw away the ones I don't need (this probably isn't a big deal).