Mac: There are plenty of solid SSH apps for the Mac, but Shuttle is an app that keeps things remarkably simple. It provides you with a quick shortcut to all your SSH servers, and not much else.
Shuttle lives in your menu bar, and offers a very simple menu. Just select the host you want to SSH into, and Shuttle connects you. You can also save your settings in Dropbox so it syncs across multiple computers. Shuttle is a very simple utility that doesn't do much else, but it works fantastically well as a shortcut menu .