Is it possible to identify usernames whose posts I don't want to be visible when I view forum threads? For example if I never want to view any posts by username X, can I enter that username somehow to cause his posts to not appear?

Yes. Click on the member's name, then View profile, and then Ignore this user.

As a result, the body of each post by that person will be hidden from view; in its place will be a link allowing you to toggle it into visibility if you choose.

The Ignore feature doesn't conceal ignored posters' names, their avatars, or anything they write that gets quoted by somebody else.

Steven

Thanks, that's exactly what I was looking for.