1. A method of implementing an item catalog hosted by a merchant website, comprising: under control of one or more computer systems configured with specific executable instructions, determining one or more items within the item catalog that are related to a particular item within the item catalog; determining tags that users of the merchant website have previously associated with the one or more related items; and suggesting that the tags that are associated with the one or more related items be associated as tags with the particular item, wherein the suggesting includes: assigning weights to the tags that are associated with the one or more related items based at least in part on a source of each of the tags and whether each of the tags was already associated with the particular item; ranking the tags that are associated with the one or more related items based at least in part on the assigned weights; and presenting at least a portion of the tags that are associated with the one or more related items to a user of the merchant website based, at least in part, on the ranking to enable the user of the merchant website to associate one or more of the tags with the particular item.