If you're talking about the German layout and AltGr, then so are the []{} keys, which are already used quite a lot in PHP programming.

It's the main reason why, even though my phyiscal keys are in German layout, I still have the USA layout in software. It's just nice to be able to make [] with a single key press :)

Agreed. Although function-¥ does give my hands a stretch now and then, I don't want to be typing it constantly..