I used to play Tyranids back in 4th/5th edition but have always wanted to make my own custom space marine force. I developed my army's backstory and in my mind I always imagined them with the ponytails you would see from old 30k art and even some chaos models.
(like this
http://store.miniwargaming.com/images/P/newimage.asp-543.gif )
I also designed my army with a similar concept from the Night Lords where instead of decorating their army with glorious sigils and emblems, they decorate themselves with skulls and spikes. I think I got the idea of this from lots of black metal bands wearing spiked arm and knee guard
lol
I was even considering just using some chaos models but play them as loyalists because I don't think you can get the hair plumes as individual bits. Anyone done anything like this before? I'm not too great on conversions and the such.
And as a related/side question: Is there any special customization you give your army besides just painting them their own colors?