I have a Windows-based browser that points to a singe website on which I post resources for users. See it in action (download and use it) here:
[url removed, login to view]
I was thinking about commissioning a MAC version, but I think it would be better to do one in Adobe Air so that it can be used on Windows and Mac platforms.
Points to note:
1) The website source url must be hidden from users
2) Followed links would open in the user's default browser. See: [url removed, login to view]
3) Ideally, the browser would open one url (for registration) on first running and on another url thereafter - but this is not essential
Ignore 3), it's not necessary at all. The browser would have no address bar or navigation apart from a 'close' button.