I would love to have something similar to the LibraryThing forum where the first messages are at the top so you can follow the thread, but each time you log in the new messages since your last visit are highlighted in a different color so you can immediately jump to where you last were and read from there.

The reason I haven't done what the LibraryThing forum does, is that it's not clear to me at all how to determine "when you last visited". Is that:

1) when you last viewed the overview of this forum
2) when you last went to the "my forums" page
3) when you last logged into BM
4) when you last wrote a message on this forum

The situation is complicated by the fact that you might opt to get email copies of forum activity, so you're actually "up to date" when you visit the forum, because you've read your email, but the site doesn't know that and thinks your last visit was when you last came to the site.

In other words, it's very complicated.

I'm still working on this, fear not, but my next step is to make it easier to see XX days of activity on all your forums.