two domains for same website

[New]

Hi,

I was thinking about the following and i was wondering if more people are doing this and if search engines see this as positive of negative.
If you have a main website with one domain. And you would like to have another website with another domain which basically functions as a click through to the main website. The click through website has one or two pages with short descriptions about the different pages of your main website and with a link under these despcriptions to the pages of this description.

If anybody knows....
thanks in advance!