CheatSheet is lets you view available keyboard shortcuts in your current application. Just hold the ⌘-Key a bit longer to get a list of all active short cuts of the current application. It's as simple as that.
Alfred is an award-winning app for Mac OS X which boosts your efficiency with hotkeys, keywords, text expansion and more. Search your Mac and the web, and be more productive with custom actions to control your Mac.
Shortcuts.design is a small website that lists every shortcut a designer ever wants to know, all designapps in one place and in a simple and clear way. It's very usefull for beginning designers to quickly charge their workflow, when you switched to a new designtool or when you just want a reference for repeating actions!
Pretzel is Mac desktop app that shows and find keyboard shortcuts based on your current app.
Macro is a Chrome extension that makes users more productive on the web through keyboard shortcuts.
Macro offers powerful website-specific shortcuts and instant keyboard shortcut discovery across many websites. Think Reddit Enhancement Suite for the web. Learning one website's shortcuts means you won’t have to learn it again for a new website.
Common Shortcuts is a simple tool for those who use the same software everyday but never remember the shortcut for common tasks.
Diamond is a tool for Mac and Windows that helps you search through all your files and mails, offline and on the cloud with ease.
Mokey is a tool to visualise Mac shortcuts.