Over the years, I have obsessively built or contributed to a number of handy resources for PL/SQL developers. Here are links and descriptions to the best of my creations:

• Quest Code Tester for Oracle - Code Tester automates the process of building and running tests of your PL/SQL programs. The major breakthrough achieved by this tool is that you describe the expected behavior of your program through a graphical interface, and then Code Tester generates the test code needed to implement those tests.
   
• Quest CodeGen Utility - Freeware from Quest Software, the CodeGen utility is, in essence, a very generalized "Design Pattern Factory." That is, you can use the Code Generation Markup Language (CGML) to capture a pattern in your code (a piece of code you find yourself writing over and over again). Then you generate the code (PL/SQL, Java, HTML, XML...whatever!) based on that pattern for your specific database object. CodeGen comes with hundreds of pre-defined patterns or templates, including the QDA or Quest Development Architecture, templates that implement a table API for your underlying datasets.   
    
• Quest Error Manager - When I built CodeGen, I included in its table API templates a generic error management framework. To make it easy for you to take advantage of this framework, I extracted it from CodeGen and packaged it as its own standalone utility. Use QEM to raise, handle, log and communicate to your users errors in a consistent and effective manner. The most important concept inside QEM is that you trap and log information about instances of errors, and not just the Oracle error.
   
• PL/Vision - "The PL/Vision Code Library provides over 1,000 PL/SQL functions and procedures that extend the capabilities of the PL/SQL language. Easily mastered by developers with any level of PL/SQL experience, PL/Vision integrates seamlessly into your development environment. PL/Vision's reusable and cleanly encapsulated packages dramatically accelerate development, simplify maintenance and increase program reliability." PL/Vision is old, but you will still find lots of handy utilities in it. You are welcome and encouraged to change it to meet your needs.
   
• The Demo Zip - A collection of all the scripts I have gathered together over the years and reference in my presentations (available here).
   
• utPLSQL - utPLSQL is PL/SQL's analogue of Java's Junit. It is, in other words, an open source unit testing framework , based on Extreme Programming principles. I wrote utPLSQL back in 1999 and released it to the world. Since then hundreds, and perhaps thousands, of PL/SQL developers have used it to write extensive test packages and achieve a high level of regression testing in their applications. The major downside of utPLSQL is that you still have to writes lots of test code.