Topic grids = pages that list topics (like new posts, new topics).
We added two key changes to them (other than visual ones):
1) Read tracking. Topics with replies since you last logged out, and since you last read them are marked "new" and if you click on that it will take you to the first unread post.
The new posts page and the new topics page both place these at the top of the list now, so if you read a topic it goes below the unread topics.
2) Forum filtering. This we are still tweaking, but the basics are that the "My Forums" on the home page are automatically added based on your activity, but you can add/remove them (on the forum page itself).
Then the new topics and new posts lists can be filtered to only topics from these forums (so if you want it just about philosophy you can make it that way, if you don't want word games, you can make it that way).
The presentation of this part is still a bit rough, so is the new topic item layout (with the columns) so let us know what you think of that.