13. A system for analyzing content items, the system comprising: at least one processor; a component configured to receive an indication of a plurality of content items; a component configured to, for each of the plurality of content items, identify at least one content element of the content item, and for each identified content element of the content item, extract information for the content element, compute a plurality of semantic feature values for the content element based at least in part on the extracted information, compute a plurality of visual feature values for the content element based at least in part on the extracted information, and store the feature values computed, for the content element, based at least in part on the extracted information; a component configured to receive an indication of a first set of content items, wherein each content item of the first set of content items is a member of the plurality of content items; a component configured to, for each pair of content items from among the first set of content items, apply a similarity function to the pair of content items to generate a similarity value for the pair of content items, and store, in association with each content item of the pair of content items, the generated similarity value; and a component configured to, for each content item of the first set of content items, identify a set of similar content items based at least in part on the generated similarity values, and store, in association with the content item, references to at least one content item of the identified set of similar content items, wherein each of the components comprises computer-executable instructions stored in a memory for execution by the at least one processor.
13. A system for analyzing content items, the system comprising: at least one processor; a component configured to receive an indication of a plurality of content items; a component configured to, for each of the plurality of content items, identify at least one content element of the content item, and for each identified content element of the content item, extract information for the content element, compute a plurality of semantic feature values for the content element based at least in part on the extracted information, compute a plurality of visual feature values for the content element based at least in part on the extracted information, and store the feature values computed, for the content element, based at least in part on the extracted information; a component configured to receive an indication of a first set of content items, wherein each content item of the first set of content items is a member of the plurality of content items; a component configured to, for each pair of content items from among the first set of content items, apply a similarity function to the pair of content items to generate a similarity value for the pair of content items, and store, in association with each content item of the pair of content items, the generated similarity value; and a component configured to, for each content item of the first set of content items, identify a set of similar content items based at least in part on the generated similarity values, and store, in association with the content item, references to at least one content item of the identified set of similar content items, wherein each of the components comprises computer-executable instructions stored in a memory for execution by the at least one processor. 15. The system of claim 13 , further comprising: a component configured to, for each content item of a first set of similar content items identified for a first content item, store an indication of the content item of the first set of similar content items in a lookup table, wherein the indication is referenced in the lookup table by an indication of the first content item.