GUIs
Obsidian
Obsidian is a free and highly extensible note taking application that uses simple Markdown files for storage.
It offers a commercial add-on for syncing with mobile apps on iOS and Android, but if you don't need that, it's free for personal use (and $50/year for commercial use).
You start Obsidian with Super + O.
Pinta
Pinta is a basic image editing tool that's great for cropping, resizing, and other basic manipulations. Just don't expect a Photoshop alternative. But it's still got a Magic Wand and layers!
You start Pinta via the application launcher (Super + Space).
LocalSend
LocalSend lets you send files to other devices on the same network running the app, like Apple's AirDrop. It's cross-platform, though, so you can send files to and from Windows, macOS, Android, iOS, and of course Linux.
LibreOffice
LibreOffice is a complete office package with word processor, spreadsheet, presentations, drawing application, and more. It's compatible with files from Microsoft Office, so this is a great way to be able to open those Word documents.
You start LibreOffice via the application launcher (Super + Space).
Signal
Signal is the pioneer of E2E encrypted messaging, and a great communication option for anyone who'd prefer not to go through one of the big tech conglomerates.
You start Signal with Super + G.
mpv
mpv is a simple, fast media player that'll play almost anything from any source. Great for watching videos.
You start mpv via the application launcher (Super + Space) or just double-click on a video in the file manager.
OBS Studio
OBS Studio lets you record or stream video from multiple inputs. You can mix a screencast with a webcam with a microphone input. It's what was used to record the Omarchy screencasts.
You start OBS Studio via the application launcher (Super + Space).
Kdenlive
Kdenlive is an excellent video editor. Perfect for working on video that comes out of OBS Studio before sharing it.
You start Kdenlive via the application launcher (Super + Space).