I've encountered a problem with LaTeX fragments: the default
resolution that dvipng produces results in text (in the images)
which is too small. Of course, browsers (eg, firefox) can manipulate
font size from the client side, but that doesn't affect images (and
changing the relative size of the two). Monitor resolution is also a
factor. Uugh. I guess mixing text with images containing text is not
really ideal, but I'll put that aside for now.

I don't have a great solution for this, but I needed something to
make it usable. I've added a little hack that creates a variable,
org-export-LaTeX-fragments-resolution, that is used in the call to
dvipng. I've found that a setting of 150 is much easier on my eyes
than the default (which I've estimated to be ~86). I added something
to org-export-plist-vars for publishing too, but that doesn't seem
to work -- not sure why (I'm new to Elisp).

The patch is attached in case anyone else was looking for a fix for
this.

Dan