1. A search retrieval system comprising: a search engine module configured to determine search results based on an inputted search term; and a clustering module configured to: form a limited size hierarchy data structure using the search results; assign a number of hierarchy locations for each search result in the hierarchy data structure; cluster the search results in the hierarchy data structure by assigning the search results to particular groups that are related based on proximity; limit a hierarchical depth of the clustered hierarchy data structure to reduce hierarchical results for presentation; and output the clustered hierarchical data structure as a list of search results for presentation.