"No suitable driver" usually means that the JDBC URL you've supplied to connect has incorrect syntax or when the driver isn't loaded at all.
When the method getConnection is called, the DriverManager will attempt to locate a suitable driver from amongst those loaded at initialization and those loaded explicitly using the same classloader as the current applet or application.(using Class.forName())
For Example
import oracle.jdbc.driver.OracleDriver;
Class.forName("oracle.jdbc.driver.OracleDriver");
Also check that you have ojdbc6.jar in your classpath. I would suggest to place .jar at physical location to JBoss "$JBOSS_HOME/server/default/lib/" directory of your project.
EDIT:
You have mentioned hibernate lately.
Check that your hibernate.cfg.xml file has connection properties something like this:
<property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:orcl</property>
<property name="hibernate.connection.username">scott</property>
<property name="hibernate.connection.password">tiger</property>