Hook into forumadmin.
 

I am trying to find out if it is possible to hook into the forum manager page. To add options to the dropdown.

Example:

http://pwcextreme.com/images/hook.JPG

I've had no issues hooking into the actual forumadmin_edit and the other pages but I don't see a hook for that page.

Unfortunately it doesn't look like there's any hook that would allow you to just modify that menu. You could do it by editing admincp/forum.php, or if you really want to use hooks you could copy all the code for the do == 'modify' section to a plugin using hook forumadmin_start and then modify that code.