I have lately found myself writing my own custom plugins and found that it is a bit cumbersome when it comes to choosing the correct values for the plugin and plugin_sid tables as you need to query the different tables to find what you need (Not sure how you guys go about).
I have written a web app aimed at plugin developers to make this easy for us. Basically you just drop the web app folder in your ossim's apache directory and you have a web interface where you can choose classifications, categories, subcategories etc. from a couple of dropdowns (populated from ossim's DB) and it will generate the SQL for the plugin and plugin_sid table for you.
I have licensed it under MIT so please feel free to contribute if you want. It is currently meant for developers and not to be used in a production environment. I will later add some additional functionality and iron out any issues as I go along. If you find any issues or need some functionality please contact me on github.