CSS
- Yahoo UI CSS Reset
- resets default CSS properties for all HTML elements (overriding browsers' default values)
- ensures custom CSS stylessheets will provide the same results on all browsers
Javascript
- Awesomeplete (GitHub) - autocompletion in input forms
- bLazy (GitHub) - lazy loading for thumbnails
- qr.js (GitHub) - QR code generation
PHP
- shaarli/netscape-bookmark-parser - Netscape bookmark parser
- RainTPL - HTML templating for PHP