Here is the list of tools I often use and I think they are superuseful:

For documentation preparation

• Doc converter Pandoc link
• Writting Markdown sintax link
• Interface Vim link
• Formating Latex link

Programming

• Interface Vim link
• gdb Plug-in gdb-dashboard link
• Vim Plug-in cscope link

Vim-like

• Firefox Navigation vimperator link
• Document Viewer zathura link
• File Manager vifm link

Others

• Wrapper for pacman and the AUR packer link
• Calendar gcal link
• Image Viewer feh link
• Terminal tilda-terminal link
• Security Sandbox firejail link