Check for Database leaks

[dreampolice]

I am always checking if any of my Java Web applications have any Database leaks with our Oracle 9i database.

Here is what I use in SQL Plus:

select username, program from v$session where username = 'myUserSchemaName';

If I dont close my connections and do alot of inserts and updates in my Web Application, the query will show many lines of JDBC Thin Client showing up.
When I do close my connections correctly and do alot of inserts and updates in my Web Application, the above query doesnt show any programs running so I assume I dont have any database leaks?

This is my way and would like to know how experienced Oracle people check to make sure there are no Database resource leaks?