You use Opera? Good. Go to
* Settings
* Preferences
* Advanced
* Content
Check the checkbox that says Enable plug-ins on demand. This is the plugin setting you always wanted. It replaces all plugins (say, annoying flash ads) by a little play button which you can click to activate the control. This way, all plugins are disabled by default (and that's good, because most of them are annoying), and whenever there actually is a plugin that you want to use, just click the play button and play your silly flash game if you must.