1. A system for categorizing items, the system comprising: a data store that stores item information for items; a computing device operating a network-based service and in communication with the data store, wherein the network-based service is operative to: receive a request for at least one category recommendation for an item of interest, the request including item information regarding the item of interest, wherein the item of interest is an item offered for sale using the network-based service; and submit the received item information to a categorization service; and the categorization service in communication with the network-based service, wherein the categorization service is operative to: generate an item vector from the item information according to a vector space model; compare the item vector to at least one category vector representing a description of an item category according to the vector space model, wherein the item category is maintained by the network-based service and associated with a plurality of items; determine the item category to be the at least one category recommendation if a similarity between the item vector and the at least one category vector is greater than a threshold value; and distribute the identified at least one category recommendation so as to enable a human reviewer to electronically select an item category from the at least one category recommendation for assignment to the item of interest.