Web Development Bookmarklets
These bookmarklets let you see how a web page is coded without digging through the source, debug problems in web pages quickly, and experiment with CSS or JS without editing the actual page.
(To keep bookmarklets in order to use them on other web pages, drag them to your Bookmarks Toolbar. Or, install them all at once.) http://www.squarefree.com/bookmarklets/webdevel.html