I have been using:
<a href="https://stackoverflow.com/questions/8174282/.">link</a>
Have yet to find a case and/or browser where it does not work as intended.
Period means the current path. You can also use .. to refer to the folder above the current path, for instance, if you have this file structure:
page1.html
folder1
page2.html
You can then in page2.html write:
<a href="https://stackoverflow.com/questions/8174282/page1.html">link to page 1</a>
EDIT:
I’m not sure if the behaviour has changed or if it was always like this, but Chrome (and maybe others) will treat periods as described above as regarding directories, not files. This means that if you are at http://example.com/foo/bar.html you are really in the directory /foo/ and a href value of . in bar.html will refer to /foo/ rather than bar.html
Think of it as navigating the file system in a terminal; you can never cd into a file 🙂
EDIT 2:
It seems like the behaviour of using href="https://stackoverflow.com/questions/8174282/." is not as predictable anymore, both Firefox and Chrome might have changed how they handle these. I wouldn’t rely entirely on my original answer, but rather try both the empty string and the period in different browsers for your specific use and make sure you get the desired behaviour.