1. A method, comprising: detecting, based on an analysis of content of a web page of a first web site, that the page includes a user-selectable link to a product page of an electronic catalog hosted by a second web site, said detecting comprising determining that the link has a URL that matches a signature of product pages of the electronic catalog; extracting from the user-selectable link a product identifier corresponding to a product; retrieving from the electronic catalog, based on the extracted product identifier, catalog content associated with the product; causing the page to be supplemented with an overlay display object that includes the catalog content associated with the product, such that the overlay display object is displayed in association with the user-selectable link; and providing, for display within the overlay display object, active content that enables a user, via a user computing device, to purchase the product by interacting with the overlay display object on the page without navigating away from the web page of the first web site; said method performed by execution of instructions by computer hardware.