Counts-as Army ideas, part 1 - Introduction

As a firm proponent of counts-as armies, I thought I'd do a series exploring some ideas for them for fun, to explore the concept and for a bit of a challenge. I'll try to come up with an interesting (at least, to me!) counts-as army using each 40K codex. I don't have them all (for shame...) but think I know enough to present the basic idea.

Some example armies others have done:

Kenton Kilgore's Dvergar, a not-squat xenos race using the Ork codex:
http://www.fightingtigersofveda.com/aotjdvergar.html

Kenton's Kurindans, lizards using the Tyranid book:
http://www.fightingtigersofveda.com/themekurindans2.html

Gorgon's Genestealer Cult, another use of the Ork codex:
http://www.dakkadakka.com/wiki/en/Gorgon%27s_Genestealer_Cult

So, the armies I'll need counts-as ideas for:
Chaos Daemons
Chaos Space Marines
Daemonhunters
Dark Eldar
Eldar
Imperial Guard
Necrons
Orks
Space Marines
Black Templars
Blood Angels
Dark Angels
Space Wolves
Tau Empire
Tyranids
Witch Hunters

So, sixteen different armies. First up, Chaos Daemons!