Easy way to demo a site for a client?

I want to have a quick way to show clients what there site will generally look like and demo aspects like a slideshow or other JavaScript
interactions web-fonts etc etc… Now that I am using css3 and html5 I really don’t use Photoshop or fireworks for layout just build individual graphics for the sites now that I’m building responsive sites and use css3 for a lot of what I use to do in the graphic programs. I can whip up something for them in code faster then doing a prototype or wireframe Ps or Fw.

I was thinking of making a sub-domain on my site and using that for demonstrations.
Any body else have this problem and maybe a better solution?

Do they need full interaction or just visuals? I’ve read multiple stories of customers stealing demo sites or templates during production and later refusing payment. Make sure you are able to prevent them from intentionally or accidentally taking a production ready version of the site or template until the work is accepted and they have paid in full.

Thanks that’s good advice
“Do they need full interaction or just visuals?”
I have a JavaScript slideshow with various transitions I wanted them to see.