Topic management is the task of gathering, evaluating, organizing, and sharing a set of web sites for a specific topic. Current web tools do not provide adequate support for this task. We created the TopicShop system to address this need. TopicShop includes (1) a webcrawler that discovers relevant web sites and builds site profiles, and (2) user interfaces for exploring and organizing sites. We conducted an empirical study comparing user performance with TopicShop vs. YahooTM. TopicShop subjects found over 80% more high-quality sites (where quality was determined by independent expert judgements) while browsing only 8 1% as many sites and completing their task in 89% of the time. The site profile data that TopicShop provides - in particular, the number of pages on a site and the number of other sites that link to it - was the key to these results, as users exploited it to identify the most promising sites quickly and easily.