OK, hi again,

I realize I've been asking lots of question and generating a certain amount of noise. Many thanks for help you've all given in last little bit. I've finally moved over entirely reveal.js and org-reveal (it's so great!) and want to be sure that my presentations all work (a) locally, on my laptop, and (b) accessible online, for my students to examine afterwards.

Most of my images are just stolen from the web, but occasionally I modify or generatethem myself. In this case they live in a local directory. I can easily sync these with org-publish-attachment, but only if I enter the links properly with C-c C-l.

The worg tutorial suggests:

Same is true for images. To add an image, put it in =~/org/img/test.jpg= and
  refer to it by
  : [[file:img/test.jpg]]
When entered this way, file links are ocnverted to html relative links.

I've tried this, but it seems as though emacs's file completion doesn't 
recognize this link style, and I don't get completion. Since I almost never know

the name of the file I'm attaching, I get frustrated and enter a

file:///home/matt/...

link, which doesn't get altered on export.  Is there a better solution?

Thanks as always!