Friendly, usable websites:
Many people like the look of website text with a clean white background, but people with dyslexia often prefer a pale coloured one. Although modern browsers let you set your own preferred background, this was not always the case, and we wrote a simple, intuitive one-click tool for this which is still used on a couple of live sites.
Usability issues sometimes get overlooked in the rush to create a visually attractive site. But it's not an either/or: you can look good and still be AA-compliant with the Web Content Accessibility Guidelines (WCAG).