Keyboard shortcuts are great. They let you do things on your Mac faster, letting you get to more stuff in less time. In Safari, for example, Command-1, -2, -3, and so on will open the sites in the Bookmarks Bar in order, from left to right.
There’s a Favorites Bar in the OS X Mail app that works similarly. You can drag Mailboxes that you use often to it. To show it, go to the View menu in Mail and choose Show Favorites Bar..