1. A computer-implemented method, comprising: at a client computer having one or more processors and memory storing programs executed by the one or more processors, receiving user instructions to associate each of a first virtual channel and a second virtual channel with a first content provider, wherein the first virtual channel includes a first set of user-specified search criteria and the second virtual channel includes a second set of user-specified search criteria that is different from the first set of search criteria; continuously performing operations according to a predefined schedule, the operations including: receiving a first set of information items from the first content provider, wherein each information item includes a document title, a document summary, and a document link to a document at a respective remote location; for each of the first set of information items, retrieving the document identified by the corresponding document link from the respective remote location; applying the first set of search criteria to each of the first set of information items and its associated document to generate a first set of search results, wherein the first set of search results includes a first set of chunks within a first document and a third set of chunks within a second document, and each of the first set and the third set of chunks satisfies the first set of search criteria; applying the second set of search criteria to each of the first set of information items and its associated document to generate a second set of search results, wherein the second set of search results includes a second set of chunks within the first document, and each of the second set of chunks satisfies the second set of search criteria, wherein there is at least one difference between the first set of chunks and the second set of chunks; associating the first virtual channel with the first set of search results and the second virtual channel with the second set of search results, wherein there is at least one search result associated with both the first virtual channel and the second virtual channel; displaying the first virtual channel and the second virtual channel on the client computer; in response to a user selection of the first virtual channel, displaying, at least partially, information items associated with the first set of search results and the first set of chunks within the first document and the third set of chunks within the second document to the user; and in response to a user selection of one of the first set of chunks, displaying, at least partially, the first document including the user-selected chunk to the user adjacent to the display of the first set of chunks and the third set of chunks, wherein the user-selected chunk is visually distinguished from the rest of the document.
3. The method of claim 1 , further comprising: displaying a search box associated with the user-selected first virtual channel; receiving one or more user-specified search keywords; identifying chunks satisfying the user-specified search keywords within the first set of chunks; and displaying the identified chunks and their corresponding information items to the user.