regarding the demo

I just checked out the demo and I can't find an example with variations. they are possible aren't they? multiple variations even as in color and size? anyone has a link to a live implementations of variations?

I'd like to have a look...

Besides, I have a client right now that wants some "preview" option, i.e. he is selling t-shirts you can customize with logos and/or text and he'd like to offer a preview of the product before ordering, anyone seen anything like that even if it was another os commerce solution?