11. A computer-implemented method comprising: generating, based at least in part on a co-occurrence analysis of search histories associated with an electronic catalog, a cluster of item descriptors describing types of items in the electronic catalog that tend to be searched for in the electronic catalog in combination, the cluster of item descriptors including at least a first item descriptor representing a first item type and a second item descriptor representing a second item type; generating, based at least in part on the cluster of item descriptors, a plurality of item clusters, each item cluster including a plurality of items in the electronic catalog and including at least a first item of the first item type and a second item of the second item type; and providing a catalog item recommendation based at least in part on the plurality of item clusters, said method performed by an electronic catalog system comprising one or more computing devices.
11. A computer-implemented method comprising: generating, based at least in part on a co-occurrence analysis of search histories associated with an electronic catalog, a cluster of item descriptors describing types of items in the electronic catalog that tend to be searched for in the electronic catalog in combination, the cluster of item descriptors including at least a first item descriptor representing a first item type and a second item descriptor representing a second item type; generating, based at least in part on the cluster of item descriptors, a plurality of item clusters, each item cluster including a plurality of items in the electronic catalog and including at least a first item of the first item type and a second item of the second item type; and providing a catalog item recommendation based at least in part on the plurality of item clusters, said method performed by an electronic catalog system comprising one or more computing devices. 14. The computer-implemented method of claim 11 , wherein the search histories collectively comprise at least millions of search requests.