44. The method of claim 29 wherein the providing of the information identifying the user-defined first group of multiple items to the user is performed in response to determining that the user-defined group satisfies one or more search criteria specified by the user, the one or more search criteria including an indication of at least one of the determined one or more first categories for the user-defined group.
29. A computer-implemented method, comprising: determining, by one or more configured computing systems, one or more first categories for a user-defined group of multiple items, the user-defined group being defined by a user that is one of multiple customers of an item ordering service that makes the multiple items available to the multiple customers, at least one of the multiple items being associated with one or more second categories that are not included in the one or more determined first categories; providing, by the one or more configured computing systems, information for display to the user identifying the user-defined group of multiple items as a single item to be ordered, wherein the information, when displayed, indicates an action that is to be performed to order the user-defined group of multiple items from the item ordering service as the single item; and after performance by the user of the indicated action, initiating, by the one or more configured computing systems, an order for the user-defined group of multiple items for the user.