1. A method comprising: extracting metadata attributes and associated attribute values from web search results, the web search results returned in response to a search request submitted by a user from a computer of the user to a web search engine, the search request comprising search criteria input by the user to the search engine, the search request input by the user using a user interface to the computer, the web search results comprising entries organized into a results list, each entry comprising data extracted from a data object searched by the web search engine and meeting the search criteria, the metadata attributes and associated attribute values extracted from the data objects corresponding to the entries of the results list, each metadata attribute comprising one or more associated attribute values, each metadata attribute comprising a category, each associated attribute value comprising value that corresponding to an associated metadata attribute, wherein the search request of the user does not include, in the search request, the metadata attribute and associated attribute values returned by the web search engine; prioritizing one or more of the extracted metadata attributes and the attribute values, wherein one or more of: the metadata attributes are prioritized based on a number of times attribute values of each metadata attribute occurs in the results list, wherein the metadata attributes are organized so a metadata attribute with a largest number of attribute value occurrences is displayed first in the display of metadata attributes to the user; and the metadata attributes are prioritized based on a number of occurrences for each metadata attribute and wherein presenting the metadata attributes to the user further comprises presenting a subset of metadata attributes to the user, the subset comprising metadata attributes occurring most often in the results list; presenting the prioritized extracted metadata attributes to a user for selection by the user, the prioritized extracted metadata attributes presented to the user on a portion of an electronic display displaying the web search results; receiving input from the user indicating a selected metadata attribute of the metadata attributes; presenting attribute values associated with the selected metadata attribute to the user for selection by the user, the extracted attribute values of the selected metadata attribute are presented to the user on a portion of an electronic display displaying the web search results; receiving input from the user indicating a selected attribute value of the attribute values associated with the selected metadata attribute; filtering the web search results based on the selected attribute value, wherein each entry in the filtered web search results comprises the selected attribute value; and displaying a filtered results list to the user, the filtered results list comprising the filtered web search results.