Recommendation systems are special personalization tools that help users to find interesting information and services in complex online shops. Even though today?s e-commerce environments have drastically evolved and now incorporate techniques from other domains and application areas such as web mining, semantics, artificial intelligence, user modeling and profiling, etc. setting up a successful recommendation system is not a trivial or straightforward task. This paper argues that by monitoring, analyzing and understanding the behavior of customers, their demographics, opinions, preferences and history, as well as taking into consideration the specific e-shop ontology and by applying web mining techniques, the effectiveness of produced recommendations can be significantly improved. In this way, the e-shop may upgrade users? interaction, increase its usability, convert users to buyers, retain current customers and establish longterm and loyal one-to-one relationships.