How can I view the output of a command on a file when visit-file?

[Stephen Eglen]

Hi,

There is a file on emacswiki that when you visit a file foo.doc, it will
run the antiword program and view that output, rather than the binary
contents of the file.

  http://www.emacswiki.org/cgi-bin/wiki/no-word.el

Likewise, if you visit a .png file, doc-view mode renders the image (and
allows you to see the file contents by hitting C-c C-c)

I'd like to do something similar to doc-view for a few other file types:

file.odt -> show the output of "odt2txt file.odt"
file.ods -> show the output of "odt2txt file.ods"
file.h5  -> show the output of "h5dump file.h5"

Before I reinvent the wheel with some code, I thought I'd just ask if
anyone has seen code already that handles this kind of idea?  

Thanks, Stephen