1. A method, comprising: maintaining a computerized similarity model comprising information relating to associations of electronic content with other electronic content, the electronic content comprising at least one of textual content and non-textual content, the associations resulting from executing a plurality of computerized content analyzers to extract information from the electronic content, each content analyzer being associated with at least one similarity metric usable to determine a type or degree of similarity of electronic content; with a computing device, determining a plurality of similarity types based on an input or source content, each similarity type relating to a different characteristic of the input or source content; weighting each of the plurality of similarity types based on user-specific context information; identifying, using the similarity model, electronic content that has at least one association in common with the input or source content according to one or more of the similarity types; ranking the identified electronic content in accordance with the weighting of the similarity types; and outputting data relating to one or more of the identified electronic content.