20. The computer-readable storage medium of claim 19 , wherein the search expression is a first search expression; the other content items are first other content items; the user also uses a second content item, and the search expression generator is to further: receive a constituent of the second content item, wherein the second content item is also a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, an electronic message, a product description, an entertainment description, or an advertisement, having text divisible into a plurality of subtexts; and generate a second search expression based on the constituent of the second content item, to search second other content items, through execution of the second search expression, wherein the second search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts of the constituent of the second content item; wherein the second search expression is to be applied by the search engine operated on the same or a different apparatus, to the second other content items to generate a second search result.
20. The computer-readable storage medium of claim 19 , wherein the search expression is a first search expression; the other content items are first other content items; the user also uses a second content item, and the search expression generator is to further: receive a constituent of the second content item, wherein the second content item is also a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, an electronic message, a product description, an entertainment description, or an advertisement, having text divisible into a plurality of subtexts; and generate a second search expression based on the constituent of the second content item, to search second other content items, through execution of the second search expression, wherein the second search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts of the constituent of the second content item; wherein the second search expression is to be applied by the search engine operated on the same or a different apparatus, to the second other content items to generate a second search result. 21. The computer-readable storage medium of claim 20 , wherein the user also consumes a collection of content items, and the search expression generator is to further: receive the collection of content items, wherein the collection of content items comprises one or more web pages, posts to one or more social networking sites, posts to one or more blogs, posts to one or more online bulletin boards, documents, electronic messages, product descriptions, entertainment descriptions, advertisements, with each content item of the collection of content items having text divisible into a plurality of subtexts; and generate a third search expression based on the collection of content items, to search second other collections of content items, through execution of the third search expression, wherein the third search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts within content items of the collection of content items; wherein the third search expression is to be applied by the search engine operated on a same or different computer system, to the second other collections of content items to generate a third search result.