I work in a "Google School" - we use Gmail rather than Outlook; Google Docs, Sheets and Slides rather than MS Office; Chrome to browse the internet1; we have Chromebooks for students; and we collaborate using Google Drive. My line manager meeting notes go on the Drive, all staff notices and minutes and procedures and what-nots go on the Drive. I am fortunate to work in a collaboration-friendly environment.
That's not to say I'm a Google master, or that I've got best practice in the bag, and that there is nothing I can learn from this Thing - on the contrary, since I started thinking about this Thing, I have organised my Google Drive so I can easily find what I'm looking for, and I am using the Drive for my work much more than I was before.
Doodle, the other tool discussed in the this Thing, I have used a couple of times - 5 or so years ago - to organise some events (I forget what) between a number of people (I forget how many). Doodle is a simple tool for scheduling meetings - create polls to find out when people are free to meet. My memory is of a simple and effective tool that did its job well. Playing with it now, there seems to be more functionality to the app, but the underlying simplicity is still there. I like that Doodle does not require you (or your fellow collaborators) to create an account to use, and that the free-to-use parts of the app do enough to meet most needs. This is a tool that I can see myself using from time to time (such as to organise visits from local authors), but it won't be a part of my day-to-day workflow at the moment.
There is one more collaboration tool that I would not like to be without: Wiggio. It is like a social network for groups. I use it with my local school librarians network to communicate, schedule meetings, ask for advice, give advice, share files and vent. I don't use this as often as I use Google Drive, but it is a valuable tool and it's a comfort having quick and easy access to a support network across the city.
In conclusion: Collaboration, yeah!