High-Contrast Mode for wp-admin
Adds a "High contrast" checkbox to each user's profile that switches the dashboard to dark backgrounds, white text, yellow links and strong borders for that user only.
Snippet Library
Accessibility snippets for WordPress
Snippets that make WordPress easier for everyone to use: skip links, focus styles, better link text and fixes for common accessibility issues. For site owners who want a site that works with keyboards and screen readers.