Yahoo! has been using HBase for a long time in isolated instances, most notably for the personalization platform powering its homepage experiences. The introduction of multi-tenancy has lowered the barriers for all Hadoop users to use HBase. We will cover traditional use cases for HBase at Yahoo!, and new use cases as a result in content management, advertising, log processing, analytics and reporting, recommendation graphs, and dimension data stores. We will then talk about the deployment strategy and enhancements made that facilitate multi-tenancy and share our experiences in operating HBase with security enabled.