[ctviggen]

A bit on the expensive side (and located in the UK), but still has some interesting ideas:

http://www.customaudiodesigns.co.uk/articles/homecinema.html

Check out their "top tier" design:

http://www.customaudiodesigns.co.uk/cinema/cine01.htm

Given that each one of those panels is expensive, this design must cost a fortune.  

The site does provide some useful ideas, though.

[csero]

Actually it is easy to do acoustic design for MCH, as there are standards for RT60, speaker placement etc ( in short, the more dead, the better). This is definitely not true for stereo.

[ctviggen]

When I look at these designs, they seem pretty "live" to me.  However, I'm sure the panels are not only diffusive but absorptive.  I still need to get some diffusion in my room.   Someone in NYC is selling some diffusive panels, but I can't afford to buy them right now.

You're right, though, that five channel might be easier than stereo, as the live end/dead end technique isn't necessarily as valid.