15. One of an optical disk, a solid state storage device or a magnetic storage device having computer-executable instructions stored thereon which, and executed by a computer, cause the computer to: crawl documents to obtain document ranking features; crawl a profile database to collect social tags associated with a document, the profile database comprising a plurality of user profiles associated with a plurality of users, each user profile comprising the social tags associated with the document by at least one of the plurality of users, the social tags comprising a text string containing one or more terms at least one of describing, categorizing and providing information regarding the document, and being indexed and stored in user profile tables separately from the document they are associated with; determine, based on the social tags, a number ranking feature containing a number of times the document was tagged with the social tags by the plurality of users; determine, based on the social tags, a textual property ranking textual stream containing a union of all the social tags associated with the document by the plurality of users; transform the number ranking feature into a static input value by applying a normalization constant to the number ranking feature, the static input value being query independent; transform the textual property ranking textual stream into a dynamic query dependent input value that is query dependent and includes a number of times a given term in a query appears in the textual property ranking textual stream; and determine a document rank for the document by inputting the static input value and the dynamic query dependent input value into a ranking function, and further inputting the document ranking features into the ranking function.
15. One of an optical disk, a solid state storage device or a magnetic storage device having computer-executable instructions stored thereon which, and executed by a computer, cause the computer to: crawl documents to obtain document ranking features; crawl a profile database to collect social tags associated with a document, the profile database comprising a plurality of user profiles associated with a plurality of users, each user profile comprising the social tags associated with the document by at least one of the plurality of users, the social tags comprising a text string containing one or more terms at least one of describing, categorizing and providing information regarding the document, and being indexed and stored in user profile tables separately from the document they are associated with; determine, based on the social tags, a number ranking feature containing a number of times the document was tagged with the social tags by the plurality of users; determine, based on the social tags, a textual property ranking textual stream containing a union of all the social tags associated with the document by the plurality of users; transform the number ranking feature into a static input value by applying a normalization constant to the number ranking feature, the static input value being query independent; transform the textual property ranking textual stream into a dynamic query dependent input value that is query dependent and includes a number of times a given term in a query appears in the textual property ranking textual stream; and determine a document rank for the document by inputting the static input value and the dynamic query dependent input value into a ranking function, and further inputting the document ranking features into the ranking function. 19. The optical disk, the solid state storage device or the magnetic storage device of claim 15 , wherein to transform the textual property ranking textual stream into the dynamic query dependent input value, the computer-readable medium having further computer-executable instructions stored thereon which, when executed by a computer, cause the computer to input textual property information associated with the textual property ranking textual stream into a Okapi Simple Best Match 25F (BM25F) ranking function to generate the dynamic query dependent input value.