Extend Triggers

Is it possible on a predefined way to extend the trigger options ?

Right now there are:
" When either saving a new post or updating an existing post "
" After saving a new post "
" After saving an updated post "
" After deleting a post "
" When content is viewed by an authenticated user "

But for example I also wants one like:
" When content is viewed by visitor " (anonymous, not logged in)

And I can imagine many more purposes

Thanks in advance

Sincerely
Roberth Andersson
Administrator/Developer @ Jump-Gate and Webworqs, Inc