Something that came up today as a result of a thread on OTN is the fact that people sometime miss functionality that is included in the JDeveloper debugger.
I wrote about some of these features in the Oracle JDeveloper Debugger Tips (Part 1) how-to.
But a little thing that might have prevented other users from discovering these capabilities is that some of these features require the use of the OJVM (Oracle's JVM) that adds some hooks that we can use for unique functionality. This also applies for our profilers for example.
So if you want to use those make sure that under your project properties -> run/debug setting you are set to using OJVM and not the client VM.
This will enable all those features that you might have missed.
(And by the way this will also enable the profilers in JDeveloper 10.1.3)