Userscripts.org

Makes each thumbnail cycle though that video's 3 thumbnails (optionally: only on mouse hover). Additional feature to view those 3 thumbnails in the top-right (non-animated) on mouse hover.

Automatically pauses the video when you switch to a different tab or window, and automatically plays when you come back to it

Dim the Lights and watch your video in peace. Auto Dim lights setting (statusbar icon menu config). Works with Firefox, Chrome and Opera!

Allows Toggling of Youtube Comments via button. It has options now! Chrome, Firefox should both work.

Changes the background color of a page and also the color of text & links to make pages easier to read. Use F2 key to toggle the colors on and off.

Auto-load more comments. Click "Auto Load Comments" and more comments autoloads. Click "Stop" to stop loading. Toggle comments by clicking the Toggle Comments button.

Adds buttons to top-left of FB page for hiding/showing the sidebar/chat/ads from view. Script compatible with Greasemonkey/FireFox as well as Tampermonkey/Chrome. No reload of page needed to hide/show.

Toggle toy or game items on Tanga (tanga.com)

Provides a link on the page or userscript command to enable/disable this script easily

adds a big button on the left of the page to quickly hide and pause the video in 1-click.

Toggles Un/Read Mail at Indamail.hu

Creates a set of links for all of your Yahoo Fantasy leagues. You'll need to customize it with your league names and IDs. (Links replace the "Make Y! your homepage" link at the top...but seriously, who cares about that?)

Change page's color scheme to optimize for watching videos. Can toggle on/off with a hotkey

Show/hide the header, footer and sidebar tabs on iGoogle to save space! Perfect for small screens or netbooks!

Adds reply and reply-to-author buttons to Google+ comments

Use this GreaseMonkey script to reclaim the hefty area that the GMail's searchbar and Logo area take up.

Add toggles for showing/hiding @replies and #hashtags on twitter.com and brizzly.com

Add multimedia keyboard support for Grooveshark (play/pause)

Enables inline image expansion for all images. Should play nicely with userscripts that modify the DOM after it has been loaded.

Cleans up image and video galleries, leaves only thumbs. They can be individually toggled for download. - Complete application!

Adds a button to Literature to toggle the viewing area width to fill the page.

Allows you to toggle the Google Search Sidebar

A simple script that uses a key press "S" to toggle the GMail searchbar. Inspired by this great script... http://userscripts.org/scripts/show/50486

Tons of assorted developer functions ranging from button removal to element fade-ins to advanced xpath grabbers.

Modify Facebook: widen pages, remove ads/spam on homepage, move pokes and events to top of homepage. Options are set to toggle on/off.

Allows you to hide elements by double click

Fixed-font message bodies toggle for GMail (new UI/API version)

Toggle sidebar on/off on mozwiki and devmo