We have updated our free PDFviewer to version 4.0. The PDF viewer adds the ability to view PDF files to IDEA natively using the JPedal PDF library. This is the version we used for our Javaone talk on writing plugins (which can be downloaded from the site).
Version 4.0 key changes are:-
1. Search function to allow users to search documents.
2. Better toolbars.
3. Update to latest version of JPedal library.
4. Zipped copy of whole project available.
Plugin can be downloaded from inside IDEA or from out site.
Full details are at http://www.jpedal.org/idea.php