Buttons are convenient tools when you need more traditional actions. To that end, Fundamental has many easy to use button styles that you can customize or override to fit your needs.
Modal dialogs, or pop-up windows look really cool and are useful for adding content that is relevant that maybe you wish to hide until a button is clicked.
Alerts are handy elements you can drop on a page to communicate success, warnings, failure or just information. They'll conform to 100% of the container width you put them in.