Here in 2024, the transparent single-pixel .gif still has a use.

GitHub Flavored Markdown is abysmally anemic when it comes to alignment capabilities. CSS doesn't work, most HTML alignment-related attributes don't work, and Markdown itself has practically no provision for alignment. So, I just today used the transparent .gif alignment technique to vertically align the centers of download buttons and corresponding version badges in a GitHub README file.

Occasionally it's useful to know the old ways. :^)