This page is a list of software, and just general things that are awesome! This page was inspired by the suckless page under the same name.
Zathura is an awesome program. Out of the box it's basically nothing, but with extensions it can read many different formats, such PDFs, DjVu, comic books and more. It has Vim like keybindings, so it will take no getting used to if you're using a Vi like editor already.
The best window manager out there. Configured through editing C making it the most extensible window manager you could use. It comes with a built in minimal bar and keybind configuration. It also serves as a great learning experience for those interested in learning C. I have myself submitted several patches to the wiki.
Vifm is a Vim inspired terminal file manager. It is very nice to use when managing many files and directories due to the many keybinds it offers. If you've used Vim in the past you're no doubt already familiar with it. It also supports image previews using Ueberzug++. Vifm has two panes, one of which can be used for previews or just as a second pane to copy between.
Neomutt is a command line email client, which is highly customizable and can be configured with encryption and Vim like keybindings.
Cairo is really nice. It handles drawing on many different buffers, including X drawables and images. It can draw any kind of shapes you can think of including images, handle colors, transparency, and together with Pango it can also load fonts, draw text and even has XML like markup for colors and formatting. It is useful for both X and Wayland buffers.
spmenu uses Cairo and Pango as of 2.0.