12. The system of claim 9 , where the feature data includes at least one of: a font size of anchor text associated with a link, a position of the link within a document, a position of the link in a list of links, a font color associated with the link, particular word in the anchor text associated with the link, a determination of commerciality of the anchor text a type of the link, a particular word before or after the link, a topical cluster with which the anchor text is associated, whether the link leads to a target document on a same host or domain as the document that includes the link, or whether an address associated with the link includes an embedded address.
9. A system comprising: a memory to store instructions executable by one or more processors; and a processor to execute the instructions to: store feature data associated with features of links within documents where the feature data specifies one or more values for at least some of the features, and where the features are independent of user behavior, generate feature vectors for the links based on the stored feature data, store user data relating to: user navigational activity with regard to the documents accessed by one or more users, and user class data associated with the one or more users; generate, based on the feature data and the user data, a model that identifies a probability that a particular link, associated with one or more particular features, will be selected by a particular user, associated with a particular navigational activity or a particular user class, where, when generating the model, the processor is to further execute the instructions to: analyze the generated feature vectors and the stored user data in relation to selections of links made by users while viewing a document that includes one of the links and in relation to the user class data or the user navigational activity, and analyze the generated feature vectors and the stored user data in relation to users viewing a document that includes one of the links without selecting the one of the links and in relation to the user class data or the user navigational activity; and store the model in the memory.