GameEx Emulator Wiki
http://gameex.info/wiki/index.php/Category:Emulators
See above for a growing list of Emulator guides. Includes things like Command Line parameters, hotkeys and plugin details.
Be great if y'all could add to it. Every time I set up a new system/emulator, I just put any research outcomes into the relevant wiki page.
If you're going to start a new emulator, use the "Template: Emulator" as a standard. You can just edit the page and copy and paste the markup into the new emulator page. The format's recently changed, with Dolphin, Cemu and Citra showing the most recent format.