If you're looking for a kick-off point in documentation form for BC4J and the J2EE framework here is the place to go. There are four links to articles which give good background information on these topics:
Ten Key Benefits of Oracle Business Components for Application Developers
Simplify J2EE and EJB Development with BC4J
Building a Web Store with Struts and BC4J Frameworks
Business Rules in BC4J
January 2004 Archives
Since the introduction of Oracle 8i (not 9i / thanks Kai) it has been possible to define so called "Materialized Views" in the database. The idea is quite simple, namely to pre-generate all the data which a view would return before it is first needed. You can also define indexes and partitioning for the view. It becomes difficult to manage, however, when the underlying data changes frequently.
The following pdf contains all the background information and some examples for getting started.
Oracle Press have just brought out a new book for JDeveloper users. This is just a preview of the index and "Tips and Tricks" from chapter 11 of the book.
This article goes into some detail about how to interface JDeveloper and OC4J with a MySql database. It includes a couple of good examples to give you a kick-start.
Here are the Conference Notes from the Oracle 10g presentations held at the DOAG in Mannheim, Germany back in November. I'm pretty sure all the documents are in German but that won't matter to our German reader's.
Before Release 2 of Oracle 9i it was necessary to enter all OS-Directories in the init.ora file and restart the instance if you needed to change those directories. From 9iR2 the UTL_FILE package has been enhanced to allow the dynamic changing of directories without bouncing the instance and without loosing any of the needed restrictions for user/schema access to this facility. For full details on how to now use this package check out this article on the OTN.
For further examples you may also want to consult this earlier document on using the new features.
This artical gives some useful hints on tuning a database. It goes into some detail about how to track down problems in the database and then go about fixing them.
Continue reading Database Tuning.
Learning Linux? This introduction to the invaluable AWK text-manipulation tool will be invaluable. This article is full of useful examples of how to use awk in administering the system and database.
If you ever wondered what the Oracle Headquarters looks like then this should give you some idea. 
They are situated right on a lake.
With release 10g of Oracle, all support for the Rule Based Optimizer (RBO) is terminated. The Rule Based Optimizer is still there but may not be there in future releases of Oracle. The full story can be read in here on page 5 of the pdf-file under 'Collecting Data Dictionary Statistics' along with other interesting facts about the 10g release.
