Netflix-Skunkworks/go-jira[0] - Jira interface written in Go that is incredibly flexible.
bat[1] - cat with code highlighting
climate[2] - Shell swiss-army knife of tools
That last one deserves a post on its own. It's certainly not the most portable thing -- requiring that certain binaries be available for some of its functions, but it works as-is for the Linux distributions that I run and provide simple commands for getting information about things that isn't always trivial to remember (such as getting an external IP address of a host from the command-line). Silly things like remembering the CLI options for 'du' (along with the necessary '| sort ... | head -5') are replaced by 'climate biggest-files'. It replaces a mess of tools, but does so, often, by simply calling those tools with the "correct" parameters that I've forgotten.
Yes, a well authored set of aliases for the most common commands would do the same thing, but I end up using 'climate' in cases where the information I need is something I rarely need for a given task and getting that information is going to be a non-obvious exercise involving a few pipes. It's a "kitchen sink" utility with a set of commands that, for the most part, you'd find a hard time grouping them into a single theme -- a command for getting the current weather (after all, it is named climate) next to one to download all files on a web page, next to one to get disk usage stats in a variety of ways. Normally, I don't like tools like this, but this one lands as a big exception to that rule for me.
[0] https://github.com/Netflix-Skunkworks/go-jira