Not really current but the Russian Stechkin comes to mind.

Glock makes a plastic shoulder stock more or less for the 18 (Full Auto) for controllability.

Also nearing "modern", the Browning Capitan. I had one for some years (Registered SBR as per US law). The problem is that the stocks really don't do much good. The open rear sight is very close to the eye and thus blurs out for most folks and the long-range sights become quite a joke in practice. With a peep I can see how the C96 and Luger long barrel jobs might work out pretty well or at least present some value.

The Canadian military did extensive testing with their Inglis High Powers and decided the stock was a waste of time. I had plans to write an article about them and did extensive shooting with mine and came to the same conclusion. I could shoot a pistol as well w/o as with the stock. I will say I am a very good pistol shot, so maybe (?) one with really sub-par skills might find the stock useful? The only application I myself found advantageous was when very fatigued. Then it was a quantifiable help. I did this in testing while doing ski sprints. But otherwise...no.