98.css, XP.css and 7.css - A trio of CSS libraries (originating with and building off of 98.css) that can be used to recreate the UI of Windows 98, Windows XP, and Windows 7, respectively.

System.css - A CSS library inspired by 98.css that can be used to create the UI of the classic Apple System OS.

The Ultimate Old School PC Font Pack - A web resource and downloadable collection of fonts from pre-GUI computer systems. We've used this in multiple places on this site (including this page!)