Html Links Module
Installing a module is easy: Create a modules subdirectory in your data directory, and put the Perl file in there. It will be loaded automatically.
Allowing visitors to create links like this could potentially be dangerous, but I wanted to be able to include [[BookMarklet]] on my site.
When using this module, the $HtmlLinks variable is always set to 0, unless the source page is locked. Locked pages CAN be included in other pages that are editable by visitors, so long as the original source page is locked.