For versions below 5.x:
http://<Tomcat Host>:<Port>/adventnet/DataServlet
For Versions 5.x and above:
http://<Tomcat Host>:<Port>/manager/status
JVM & Thread Info:
http://<Tomcat Host>:<Port>/manager/status?XML=true
JDBC Data:
http://<Tomcat Host>:<Port>/manager/jmxproxy?qry=*:type=DataSource,*
Memory pool Data:
http://<Tomcat Host>:<Port>/manager/jmxproxy?qry=java.lang:type=MemoryPool,*
Web Application Data:
http://<Tomcat Host>:<Port>/manager/jmxproxy?qry=*:type=Manager,*
Tomcat Web Data:
http://<Tomcat Host>:<Port>/manager/jmxproxy?qry=*:type=GlobalRequestProcessor,*
Class Loading:
http://<Tomcat Host>:<Port>/manager/jmxproxy?qry=java.lang:type=ClassLoading