Distracting the cat
Our cat used to massacre the corner of the sofa, standing on its side and shredding his claws. We bought a new one, and suddenly there was motivation to do something about it. I put this scratching post right next to that corner (it's exactly the same height as the sofa) and the problem disappeared – now he only scratches on that. For some reason, he doesn't like vertical scratchers, but this one has a 'scratchable' top platform and that's exactly what we needed.
I'm buying another one, as I have one more sofa to 'protect' ;)