There are many Clojure libraries available. Additionally, Clojure can use any Java library via Java interop. Together, this provides a vast ecosystem of libraries at your disposal.
Clojure Toolbox - categorized Clojure libs
Clojars - community repo for Clojure libs
Maven Central - searchable repo of Java and Clojure libs
GitHub - search by language
These are groups of open source libraries maintained with common infrastructure, people, or goals:
Clojure contrib libs - open source libs under the Clojure umbrella project