Apparently Vorbis (.ogg) files are not all that commonplace, and some popular web servers (at least IIS7) aren't configured to handle them by default. Under the assumption that it's a case of missing MIME type I send a support request to GoDaddy (my web host of choice), who were pleasantly responsive and even helpful.

IIS 7.x supports configuration of mime-types on the application or virtual directory level by including the following lines in a Web.config file at the root of said directory:

<system.webServer>
	<staticContent>
		<mimeMap fileExtension=".ogg" mimeType="audio/ogg" />
	</staticContent>    
</system.webServer>

After making the change, all .ogg file links within this site are now accessible (this particularly pertains to the Defender of the Crown links).

This guy hooked up an old Sinclair ZX Spectrum to a bunch of crappy hardware (a hard drive array, an old dot matrix printer and a scanner) and got them to play an amusing (though still impressive) approximation of Radio Head's "Nude". Here's to a bigger geek than I can ever hope to be!