Web 2.0 users engage in collaborative tagging and associate words with the users' own and with other users' content. The result is an additional layer with descriptions of web resources. The information contained in the tag-resource associations can certainly be useful. However, we argue that current collaborative tagging systems do not support users well in navigating and exploring tag spaces, because tags are treated as independent. We suggest that different ways of displaying tags to users are needed and describe our approach to supporting users in navigating tag spaces. We illustrate our ideas with a prototype user interface.