I know that there is a link to "Mark all topics read" within each individual category and subforum, but I was wondering if it was possible to include a link that would allow users to mark all of the topics throughout the entire forum read with one click.

Thanks for any help.

Probably, just make a navigation button
Display>headers and Navigation
Add a customized menu

Use this link - http://FORUMNAME/forum.htm?mark=forums

See if it works, i am not 100% sure if it will work.

What version are you using?
All the versions have a "mark all forums read" on the front main index. It may be in a different place on diff. versions.

But what Sanket suggested should work, just copy the link for the
"mark all forums read"