Most of my work has a single highly specific consumer: me. I'll restyle websites to remove distractions and improve clarity, focus, and readability. I do this very nearly as casually as breathing now (Chrome, Element Inspector, and Stylebot FTFW).

If you'll apply those styles to a page, you'll find that:

* Links are colored. Blue colorblindness is quite rare. That's arguably a far better choice than the orange/red links I'm seeing more frequently now. For myself, I find underlines distracting.

* On hover they're underlined and the background cover shifts.

* On click, foreground and background colors are inverted.

Your point on :focus vs. :hover is probably well-taken, though those have been equivalent for my use.

I've encountered a number of sites with disappearing sub-menus (themselves an arguably broken UI element), where the rule for visibility is :hover of the/a parent element. Which means that when the pointer moves off the parent and onto the submenu, the submenu disappears. LinkedIn has been exhibiting this recently.