I am not sure if this was ever an option via the Admin Control Panel in earlier versions, but with Tiki15 we have red links! I was running Tiki14 and if I triggered a link without a destination, such as for building a page off a link, the link appeared with a question mark. I thought that was a tad confusing.
But to my greatest pleasure, upon uploading Tiki15svn, I now see red links in my wiki page. You can go to this page Tage Frid and see those beautiful red links prompting users to create those pages!
Thank you Tiki gurus!!!!!! It just keeps getting better and better!