1. A method comprising: periodically analyzing one or more data sources to identify a plurality of prior queries as fresh queries, wherein each of the prior queries was submitted as a search query a number of times during a recent time period and satisfies a criterion, wherein the criterion is a rate of change in query frequency during the time period, a deviation from an expected query frequency during the time period, or a threshold number of occurrences of the query during the time period; filtering the fresh queries to determine candidate refinement queries; in response to receiving a user query from a user, selecting from the candidate refinement queries a plurality of queries that match the user query; ranking the selected plurality of queries, wherein the selected plurality of queries are ranked based on one or more of the data source of each selected query, a quality of results associated with each of the selected queries, or a profile of the user; and providing one or more of the selected queries as related search suggestions for the user query based on the ranking.
1. A method comprising: periodically analyzing one or more data sources to identify a plurality of prior queries as fresh queries, wherein each of the prior queries was submitted as a search query a number of times during a recent time period and satisfies a criterion, wherein the criterion is a rate of change in query frequency during the time period, a deviation from an expected query frequency during the time period, or a threshold number of occurrences of the query during the time period; filtering the fresh queries to determine candidate refinement queries; in response to receiving a user query from a user, selecting from the candidate refinement queries a plurality of queries that match the user query; ranking the selected plurality of queries, wherein the selected plurality of queries are ranked based on one or more of the data source of each selected query, a quality of results associated with each of the selected queries, or a profile of the user; and providing one or more of the selected queries as related search suggestions for the user query based on the ranking. 7. The method of claim 1 , wherein the selected queries are further ranked based on a number of times during the recent time period that the selected queries were respectively submitted as a search query.