It was really wild, out of the box you would get: sound themes, color themes, icon themes, startup sounds, wallpaper themes, different loading animations, am I forgetting something? :-D
There was also "smileys" but I never used those because smileys were considered tacky. Yet it's the thing that stuck harder than anything else.
I remember them for rendering my computer almost unusable by eating up nearly all of the available compute... But my gosh it was pretty!