Stumbleupon is a brilliant downloadable toolbar that beds into your browser and gives you the chance to surf through thousands of excellent pages that have been stumbled upon by other web-users
TiddlySnip is a Firefox extension that lets you use your TiddlyWiki as a scrapbook! Simply select text, right click and choose 'TiddlySnip selection'. Next time you open your TiddlyWiki file, your snippets will be there, already tagged and organised.
Lily is a Firefox add-on that allows users to create rich, complex applications in a web browser. With Lily it's possible to make programs that mashup the web or the desktop, visualize and animate data, modify webpages, play music, or connect to world outside the computer.
KGen (Keyword Generator) is an extension that allows you to see what keywords are strong on visited web page. Than, you can retrieve them for social sharing (tag filling) or webmastering/SEO. KGen retrieves every words of a page and lets you know how many