Found some more!

livestreamer
I already knew that the lack of Flash would pose a problem with my ability to watch many videos and livestreams. With this tool, however, I just simply type in "livestreamer [stream URL] [stream quality]." A very nifty tool.

mednafen
I'm always wary of the type of emulator that emulates a variety of consoles, but this one works out perfectly fine. Using it's as simple as learning the keystrokes and hooking up a controller. I do wish, however, that it had a good front-end. It would make things easier,

RetroArch
Speaking of multi-console, command-line-driven emulators, RetroArch seems to be the most advanced one out there. It's a lot to go over, so here's the ArchWiki link.

Pacmatic
It's a wrapper for Pacman that checks ArchNews before upgrading. I didn't think I'd need this, but there was recently a system-wide change in how Arch handles ca-certificates, and Pacmatic immediately let me know to make the changes. Very handy!

packer
I use Yaourt to install AUR packages, but this is much faster if I already know what I'm looking for (if, for instance, I spot someone talking about an AUR package and they relay the name). Alongside Yaourt, it's REALLY nice.

dar
Everyone who deals with tarballs uses the tar utility. This is designed to replace it. And replace it it does. Here's the list of features it has, my favorite being support for split archives.

There's even GUI frontends for it. Perhaps I'll try one of them in the near future.