I put things out there on it and I have had success leading to interviews at companies. I had a Google Recruiter reach out to me via LinkedIn two years ago while I was still in college, and ended up going deep into their interview process. Never applied to Google, they just reached out.

I also keep up with friends/acquaintances (typically people on the 'business' side of things). Though most of my software/programming buds and gals we connect elsewhere (typically through Steam).