We frequently encounter unfamiliar entity names (e.g., a person's name or a geographic location) while reading texts such as newspapers, magazines, and web pages. When this occurs, we typically perform a sequence of tedious actions: select the entity name, submit it to a search engine, and obtain detailed information from websites. In this paper, we present Linkify, a tool that enhances text reading by automatically converting entity names into links and displaying a widget that contains links to several relevant websites. We also propose a novel method for evaluating the helpfulness of entities to users using supervised machine learning with a set of carefully designed features. Experimental results show that our method significantly outperforms existing state-of-the-art methods.