I want to have the Save extension be .sav because it's more universal, however, it doesn't work for Gameboy, which is the plugin I use the most. I am unsure whether or not it has the same behaviour for any other plugins, though I am sure that it does work for SNES and Genesis. Is this a bug in the Retrode firmware?
The next firmware release will have ".sav" as the extension for GB games, because that is what all the GB emulators I know of are using.
That's one of two little details that I merged in from justin89's patch. (The rest of the patch will still have to wait for a while, however.)