The Cobertura plugin can produce reports in html and xml formats. You can even get both is you want to. Here's how you would configure that:
<project> ... <reporting> <plugins> ... <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <configuration> <formats> <format>html</format> <format>xml</format> </formats> </configuration> </plugin> </plugins> </reporting> </project>