1. A method for searching, comprising: transforming a plurality of document identifiers and their associated set of tags into a set of URL/TAG pairs; constructing a bigraph using the set of URL/TAG pairs; using the bigraph to compute tag profiles and document profiles using spreading activation for document identifiers and tags in the set of URL/TAG pairs; for a selected tag or document, identifying a tag profile or a document profile associated with the selected tag or document, respectively; arranging by relevance those tags or documents in the identified tag profile or document profile associated with the selected tag or document, respectively.