16. A system comprising: at least one computing device; and a provider that: receives a first structured query, wherein the first structured query comprises one or more attributes values and each attribute value is associated with an attribute; determines an estimated number of items that match the first structured query; determines if the estimated number of items is below a threshold number of items; and if the estimated number of items is below the threshold number of items: determines a second structured query from the first structured query, wherein the second structured query comprises at least one attribute value that is different than the one or more attribute values of the first structured query, determines a plurality of items that match the second structured query; and provides indicators of each of the determined plurality of items, wherein the provider determines the second structured query from the first structured query by: determining a plurality of candidate structured queries from the first structured query, wherein the number of candidate structured queries in the plurality of candidate structured queries is proportional to a maximum time, wherein the number of candidate structured queries is determined by dividing the maximum time by the expected amount of time it takes to determine and evaluate a candidate structured query; for each candidate structured query of the plurality of candidate structured queries, estimating a distance between an item that matches the candidate structured query and the first structured query based on the attribute values associated with the first structured query, one or more attribute values associated with the item that matched the candidate structured query, and popularity information associated with the item that matched the candidate structure query; and determining the candidate structured query with the smallest determined distance as the second structured query.
16. A system comprising: at least one computing device; and a provider that: receives a first structured query, wherein the first structured query comprises one or more attributes values and each attribute value is associated with an attribute; determines an estimated number of items that match the first structured query; determines if the estimated number of items is below a threshold number of items; and if the estimated number of items is below the threshold number of items: determines a second structured query from the first structured query, wherein the second structured query comprises at least one attribute value that is different than the one or more attribute values of the first structured query, determines a plurality of items that match the second structured query; and provides indicators of each of the determined plurality of items, wherein the provider determines the second structured query from the first structured query by: determining a plurality of candidate structured queries from the first structured query, wherein the number of candidate structured queries in the plurality of candidate structured queries is proportional to a maximum time, wherein the number of candidate structured queries is determined by dividing the maximum time by the expected amount of time it takes to determine and evaluate a candidate structured query; for each candidate structured query of the plurality of candidate structured queries, estimating a distance between an item that matches the candidate structured query and the first structured query based on the attribute values associated with the first structured query, one or more attribute values associated with the item that matched the candidate structured query, and popularity information associated with the item that matched the candidate structure query; and determining the candidate structured query with the smallest determined distance as the second structured query. 18. The system of claim 16 , wherein the provider further: for each candidate structured query of the plurality of candidate structured queries, estimates a number of items that match the candidate structured query; and determines the candidate structured query with the highest estimated number of items as the second structured query.