They used to be common but a modern trend is to use computer algorithms to measure metrics such as email response times to gauge employee engagement levels. However, surveys remain a hallmark of high-performing HR systems. They serve at least 3 useful functions: they are great predictors of behaviour, they give employees the chance to feel heard, and they can be a vehicle for changing behaviour.
I meet many leaders who are convinced they are doing a great job and are leading motivated teams. However, when I speak with team members, another story often emerges! Of course, the best way to know where your employees are at is to build trusting relationships and have regular, open communications. Nonetheless, anonymous surveys can be a great help in identifying problems and enabling corrective action to be taken in a timely manner.
Good HBR article on this subject: https://goo.gl/124fpS