I recommend doing disaster recovery steps for your personal data as well, such as Gmail. At one point recently I was creating filters to delete bulk messages and - when the filter got created, it somehow missed the from:@xyz.com domain part and I ended up deleting => delete forever all emails. I noticed the issue right away but it was enough to wipe 2-3 months worth of emails (all of them, even Sent ones).
I simply had to download the Mac / Windows (https://teams.microsoft.com/downloads) client and things worked. I never found a "web version" of Teams - but it probably exists somewhere. :)
I tried Neo4j a while back for recommendations and calculating similarities between users but when running against our full dataset got too many OutOfMemory exceptions. Ended up with a Mahout / Spark solution. It's an awesome graph db though - can find many other uses for it.
I wanted to build something like this - basically a P2P based End-to-End encryption messaging technology (so it doesn't get inspected by peers) for use cases such as messaging (a-la SMS) on a non-networked environment such as cruise ships / National Parks, etc [maybe through bluetooth or something]. Cruise lines should / could easily build a messaging app that works on a closed network (lots of branding potential.. not sure why it hasn't been done yet!). If anyone is interested ping me. :)
At work we use a combination of git + Jenkins and a simple xcopy on build succeed. Does a great job, plus it can do Slack events, email notifications, etc.