http://www.thedarkmod.com/ Beta released. I've not got time to play this just now but had an eye on it for a while. Some of the pre-release videos I've seen look very impressive.
Regarding the service unavailable - it comes and goes. I think their servers must be busy as the beta only launched the other day.
Finally! I've been waiting for this for ages! Most of the demo hosting sites (Fileshack, Gamershell etc.) have it available if the 1st link is unavailable
"The Dark Mod", really? I remember D3 being quite dark by default as it is when I played it at launch all those years ago