I'm finishing painting whats left of my army, and I'm running out of things to keep me busy, I'd like to try my hand at creative basing, I'd like to do something involving ash or the gray sterilized sand that one sees upon the apocalyptic barren land conquered by the necron, I mean I know I could go with crushed slate, but that never really matches the scale, and putting glue and actual ashes might make a mess of things, including paint and future rust spots, any ideas?

I would suggest starting here with this article for the actual sand basing, where you can choose between a stander or more coarse base:

http://uk.games-workshop.com/warhammer/terrain-basics/5/

Then, head to this link, where it describes how to paint the sand to make it look like a proper ashen waste:

http://uk.games-workshop.com/warhammer/terrain-basics/12/

Hope this is helpful!

To make the sand look dead and sterile I suggest you try a combination of drab and pale colours. Try to avoid any warm colours such as bubonic brown or graveyard earth. A warm colour gives an impression of life or that something could live there. Black ink used to stain the sand and then drybrushed up with greys will give a very dead and drab look. Also you could have a poke about in you bits box, a few skulls or bones will make things look dead. Make sure you include no static grass of anything else which could be called a plant and therefore alive.

You copuld also try to make the place look un-kept and un-even. You can do this by adding some putty or green stuff to the bases before you add the sand/gravel or whatever. Simply a little, tiny piece of green stuff can be placed on the base and smoothed down a bit so this lump blends in with the surface of the models base. Once you put your sand over this and paint it etc you will get an effect as though the ground your models are moving over is un-even.

Even though I am covered as for the advice I can say thank you too cause everyone can use a nice tip or two! ;Y