11. A device comprising: a memory to store instructions; and a processor to execute the instructions to: receive, independent of any search query and from a first user, a selection of one or more documents, where the one or more documents are used to form a plurality of custom content groups, index the one or more documents to form a custom search index for each of the plurality of custom content groups, where each custom search index is different from a web search index and any other custom search index associated with the plurality of content groups, receive, from a second, different user, a selection of one or more of the plurality of custom content groups, receive, from a client device associated with the second user, a search query, perform, based on the search query, a search of the web search index to identify web search results, perform, based on the search query, a search of one or more of the custom search indexes associated with the selected one or more custom content groups to identify custom search results, generate a search result document that includes the web search results, the custom search results, and a plurality of advertisements presented within at least a first area and a second area of the search result document, where the first area is distinct from the second area within the search result document, where the web search results and one or more of the custom search results are included within the first area, and where the advertisements and another one or more of the custom search results are included within the second area, and provide, to the client device, the search result document.
11. A device comprising: a memory to store instructions; and a processor to execute the instructions to: receive, independent of any search query and from a first user, a selection of one or more documents, where the one or more documents are used to form a plurality of custom content groups, index the one or more documents to form a custom search index for each of the plurality of custom content groups, where each custom search index is different from a web search index and any other custom search index associated with the plurality of content groups, receive, from a second, different user, a selection of one or more of the plurality of custom content groups, receive, from a client device associated with the second user, a search query, perform, based on the search query, a search of the web search index to identify web search results, perform, based on the search query, a search of one or more of the custom search indexes associated with the selected one or more custom content groups to identify custom search results, generate a search result document that includes the web search results, the custom search results, and a plurality of advertisements presented within at least a first area and a second area of the search result document, where the first area is distinct from the second area within the search result document, where the web search results and one or more of the custom search results are included within the first area, and where the advertisements and another one or more of the custom search results are included within the second area, and provide, to the client device, the search result document. 15. The device of claim 11 , where the processor, when receiving the selection of the one or more custom content groups, is further to: provide, to the second user, a list of available ones of the plurality of custom content groups, and receive, from the second user, the selection of the one or more custom content groups from the list.