Phoenix Media (http://www.phoenixmedia.co.uk) are working on the extras. I'd urge everyone to drop them a line at email@example.com and express interest. Let them know there's a demand/fanbase out there.
One item which definitely has to be included is the fabled bloopers reel. I implore everyone to mention this specifically - it's such a rare bit of footage, and it would be fantastic to liberate it.