I have a customer who has a bunch of websites, such as islandwidgets.com, mainewidgets.com, etc..., but he would like to have them all use secure.widgets.com when using https. Is something like this possible? They would all be using the same IIS website, so I can handle it on the server side if need be, but I really don't have much experience dealing with this type of issue. Thanks.
The first thing to bare in mind is that a wildcard SSL certificate is only marginally more expensive than a standard certificate, and a wildcard certificate would resolve the issues cleanly.
If a single secure domain is required (assuming https://secure.example.com) then what you would need to do is ensure that shopping cart data is stored in the database and when the user goes to the checkout (secure site) some unique one time key is passed along with it to identify the cart in question and recall the products being sold to be processed through the checkout.