$.getJSON not working
For chrome extensions to break cross-origin policies, you need to add the domain to your manifest file via the permissions entry:
"permissions": [ "tabs", "bookmarks", "http://slu.edu/", "http://*.google.com/", "unlimitedStorage"],Source: http://code.google.com/chrome/extensions/manifest.html#permissions
You are correct in thinking this was a cross-site issue. If you look at the Chrome console, you should see something like:
XMLHttpRequest cannot load http://slu.edu/peoplefinder/json/json_index.php?q=. Origin http://jsbin.com is not allowed by Access-Control-Allow-Origin.
If you're running this on a server with scripting capabilities (eg: PHP), you can create a script on your own server which will fetch the remote data instead of doing it in the browser.