I searched for "API recommandation" and some other combinations, but no results.
I would like to see a strong recommandation for module developers, where to put what in modules. We have 3 files which almost every module has. I would like to see a few more files, which idealy, are included automaticly by the core, if they exists. These are: MODULENAME.forms.inc and MODULENAME.api.inc.
Many modules are developed VERY good, they come with REAMMEs, API.txt and so forth, but in time of development the code moves on, the API.txt might not.
I started to put "public" API stuff from my modules into an extra file, so everyone of my follow devs have a sneak into that file and pretty muchs knows what they can do with my module. The *.module file will still have enough code for block display, pages other hooks and so forth.
The only thing I don't know is if there would be an huge impact on page load if there are a couple of more files to inlcude.
Btw. I know that some modules come with MODULENAME.api.php files already, but there is only dummycode in there and I *guess* that shall help IDEs such as ZEND to provide helpers for faster development. I never use those myself.