I'm working for a small (<50 employees) company, and I'm pretty lucky to have a management that cares about this.

Stuff we've got:

- weekly all hands meetings where people talk about what makes them excited - lots of non-work-related chat rooms - 2-3 meetup opportunities per year - culture of quick ad-hoc synchronous meetings

We also had a board game night via Tabletop Simulator (http://berserk-games.com/tabletop-simulator/)

It also helps massively if the company is remote-first. We've got a central office where several employees are based but you never feel like you're missing out if you're based elsewhere.