Last week I presented a fun topic to the Madison Perl Mongers: I created a user-mode filesystem that treats PDF files as disk images, and I packaged it with PAR.
For the demonstration, I wrote a quick-and-dirty Mac GUI front end. It probably works only on 10.4 (I didn't test 10.5) and isn't as powerful as the Fuse-PDF command line, but it's more accessible.