It depends on the keyboard layout, though. To write [ I need to type Right Alt + 8.

Many of the tips involving keys like {[^$ look cool, but are impossible to hit fast on a non-US keyboard.

I highly suggests switching to QWERTY while coding in Vim. You should be already familiar with it and it only takes a few days to be really at ease with it. We don't need characters from our languages in our code (at least most of the time).

Sometimes you can hit ctrl-<key where [ is on US layout>, but I forget if/when it works that way.

Same here. ctrl-3 works also, for some reason.