Yes, near the top of the right hand (widget) column.
On the forum directory page on the "all topics" page on all 6 forum category pages on all 29 individual forum pages but not on the page for an individual topic (thread)
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .