I currently host a few dozen marketing sites on SP2010. They run on a single WebApp with Host-Named Site Collections for each client. I have a few instances now that a client may have a special vanity domain that they own that they want to mask a particular page in their current site collection. I've tried using IIS URL Rewrite module but have been unsuccessful so far, although I feel the solution has to be there somewhere. Right now, I cannot find a way to do this without creating a new site collection and replicating content or a separate IIS site that does a redirect and not a url mask. I figure that some SharePoint hosters out there have to know how to do this.
example: host-named site collection: mycompany.com wants to mask mycompany.com/myregion/pages/home.aspx with the url: coolestcompanyinmyregion.com/