Bolt is akin to PDQ Deploy in the sense that you can run scripts against multiple client types to help configure nodes in an environment. Except that bolt is agentless too!
Tool: Duplicati
Category: Backups
Website: http://www.duplicati.com
Awesome because: FLOSS software, multiple platforms (.NET/MONO-based), easy to use backup on all important cloud services (like OneDrive, Amazon S3...) and other backends (including ftp, ssh...) combined with built-in AES encryption.
It's really hard to describe Darcs in one short sentence. Hopefully I did it some justice. I included a link to a page that might help explain it or here is another one if you want to see how it compares to Git http://darcs.net/DifferencesFromGit
Terraform is awesome. You write code to create infrastructure. The tools themselves are modular and as such it has providers that allow creation of infrastructure in AWS, Microsoft Azure, Google Cloud Platform, Oracle, and many others. Terraform is *the* way that companies try to build multi-cloud solutions.
Wireguard is a new VPN based on elliptic curve crypto (Curve25519, ChaCha20, Poly1305) and public key cryptography. It has a very small attack surface and is extremely fast. It's currently used in production by Mullvad VPN and AzireVPN.
MTR is basically a combination of traceroute and ping - I've used it
frequently to diagnose routing issues between hosts, and it's come in
handy multiple times.
Added Sheepdog, which is a already mature distributed block storage, S3 Storage and distributed file systems. Created by the japanese NTT and licenced as GPL2.