1. A method comprising performing a machine-executed operation involving instructions, wherein said instructions are instructions which, when executed by one or more processors, cause the one or more processors to perform certain steps including: receiving a first set of query terms; for each vertical in a plurality of verticals, determining a number of previous searches that both (a) were performed based on the first set of query terms and (b) produced a set of search results, in the vertical, from which at least one search result was selected by a user; ranking verticals in the plurality of verticals based at least in part on said numbers determined for each vertical in the plurality of verticals, thereby generating a ranked list of verticals; selecting one or more selected verticals from the ranked list of verticals based on ranks of verticals in the ranked list of verticals; and presenting, for each particular vertical of the one or more selected verticals, one or more search results that are (a) generated based on the first set of query terms and (b) within the particular vertical; wherein the machine-executed operation is at least one of (a) sending said instructions over transmission media, (b) receiving said instructions over transmission media, (c) storing said instructions onto a machine-readable storage medium, or (d) executing the instructions.