This is a list of things I currently use or have used. You can research before you try at https://atom.io/packages/. Two ways to install. Command line apm install {package name] or in Atom, goto Edit > Preferences > Install and search for your package.
atom-beautifyautocomplete-modulesautocomplete-pythonmarkdown-writerminimapopen-recentplatformio-ide-terminalruby-testgit-plusgit-time-machinehighlight-selectedatom-bootstrap3atom-html-previewcolor-pickerpigmentsemmetlinter- `linter-rubocop
linter-csslintlinter-htmlhintregex-railroad-diagram
ariake-dark-syntaxnew-moondracula-themegithub-atom-light-syntaxoceanic-nextseti-syntaxseti-ui
xkcd-comicsactivate-power-modeautoclose-html