1. A method for selecting at least one product for association with a document for display in a user interface rendered by a computing device comprising: analyzing at least a portion of the document with an analyzer computing device, the analysis including at least a frequency of words in the document; constructing a keyword query search string with a keyword constructor computing device, the keyword string at least partially based on words of the document having highest frequencies; searching product records in a products database with a computer search engine to identify products satisfying the constructed keyword query search string; and selecting at least one product from the identified products with a post processing computing device for display in the user interface.