Safari seems to be the only modern browser that doesn’t display the destination of links when hovering with the cursor (by default). “Where To?” is an extension that adds that functionality in a very simple manner.
After page load, Where To? processes all the links and displays their href destinations in a small status bar as they’re moused over.
Even before I started I figured this feature must be available somehow; it’s too widely used and available almost everywhere else. But I decided it’d be more fun to learn how to write a Safari extension than search for other solutions. Afterwards, I realized that this feature is, in fact, already available in Safari, it’s just disabled by default (see View -> Show Status Bar). Where To? still has its merits, though, like taking minimal browser real estate and displaying action hrefs in addition to full URLs.
So that’s that, it’s a simple extension to add a feature I was wishing for.