15. A non-transitory, machine-readable medium having machine-readable instructions thereon, which, when executed by one or more computers or other processing devices, cause the one or more computers or other processing devices to: create a specification for constructing a web display to contain page components that display data from heterogeneous data sources, the specification associating the page components with uniform resource locators assigned to the page components; store the specification in at least one memory; retrieve data from heterogeneous data sources to produce the web display; control display and/or update of the page components using the uniform resource locators, the web display to display at least some of the data from the heterogeneous data sources; associate one or more user-specific changes to the page components, the user-specific changes comprising a layout change to a page layout for a page including the page components; track the one or more user-specific changes to the page components, the page layout, searches, and text to allow users to make changes without administrative approval; and provide user-selectable options to dynamically undo at least some of the one or more user-specific changes to the page components.
15. A non-transitory, machine-readable medium having machine-readable instructions thereon, which, when executed by one or more computers or other processing devices, cause the one or more computers or other processing devices to: create a specification for constructing a web display to contain page components that display data from heterogeneous data sources, the specification associating the page components with uniform resource locators assigned to the page components; store the specification in at least one memory; retrieve data from heterogeneous data sources to produce the web display; control display and/or update of the page components using the uniform resource locators, the web display to display at least some of the data from the heterogeneous data sources; associate one or more user-specific changes to the page components, the user-specific changes comprising a layout change to a page layout for a page including the page components; track the one or more user-specific changes to the page components, the page layout, searches, and text to allow users to make changes without administrative approval; and provide user-selectable options to dynamically undo at least some of the one or more user-specific changes to the page components. 17. The non-transitory, machine-readable medium of claim 15 , wherein versions of the page are stored at a remote server.