The Twitter hashtag is a unique tagging format linking Tweets to user-defined concepts. The aim of the paper is to describe various applications of Twitter hashtags and to determine the functional characteristics of each application. Twitter hashtags can assist in archiving twitter content, provide different visual representations of tweets, and permit grouping by categories and facets. This study seeks to examine the trends in Twitter hashtag features and how these may be applied as enhancements for next-generation library catalogues. For this purpose, Taylor's value-added model is used as an analytical framework. The morphological box developed by Zwicky is used to synthesize functionalities of Twitter hashtag applications. And finally, included are recommendations for the design of hashtag-based value-added dimensions for future library catalogues.