We present an interactive multimedia interface for automatically summarizing
large corpora of evaluative text (e.g. online product reviews). We rely 
on existing techniques for extracting knowledge from the corpora but present 
a novel approach for conveying that knowledge to the user. 
Our system presents the extracted knowledge in a hierarchical visualization mode
as well as in a natural language summary. We propose a method for reasoning
about the extracted knowledge so that the natural language summary
can include only the most important information from the corpus. Our approach
is interactive in that it allows the user to explore in the original dataset
through intuitive visual and textual methods. Results of a formative evaluation 
of our interface show general satisfaction among users with our approach.