Tampermonkey

Greasemonkey compatible script manager.

30 Seconds of Knowledge

Become a better developer, in every new tab.

Conduct Exam is a robust online exam software which offers impeccable assessment solutions

Makes every page (or only pages that you want) to have light text on dark background.

Reduce eye strain in your browser with this extension that provides a dark theme for browsing.

An open source repository of design principles and methods

Styles and skins for all popular sites in the web

GreaseKit is a SIMBL plugin, that adds user scripting to Safari, Mailplane, Diet Pibb.

Customize the way a web page displays or behaves, by using small bits of JavaScript.

Modify requests, inject JavaScript and CSS into pages.

Owl is a light-weight Firefox add-on that gives webpages a dark background and dimmed colors.

Penny is a personal finance app that takes the pain out of keeping track of your finances.

Your Bookmarklets, On Steroids

Short-range anonymous messaging (Secret meets Firechat)

Chat with everyone

Stylus is a userstyles editor and manager based on the source code of Stylish version 1.5.2.

Enlarge photos, images and thumbnails in VK.

Violentmonkey is a userscript manager to support running userscripts in web pages.

A user styles manager for the Web