We use Highfive for video calls and it includes hardware that mounts on LCDs.
Slack has been wonderful. We were a really early user of Slack, and once we distributed our workforce across multiple time zones, it became really integral. It’s super lightweight, but allows us all to get out of email and stay in touch. It gives people the ambient noise and pulse of the company without actually having to be there.
Dropbox is great at its core function: syncing files correctly and not losing them. We tried some other platforms with more functionality, but we ended up losing some of our files. Dropbox does exactly what you need it to do.