A handy Eclipse plugin to search Java API docs.
With it, you can search Java API doc wthin Eclipse. Source code is associated
with the javadoc and ready to view or download.
Just extract the little docjar-1.0.zip to your Eclipse root folder(for example, d:/eclipse)
and restart Eclipse, and then follow the menu path: Windows->show view->others->DocJar->DocJar Search. Alternatively do what the screenshot shows.
It is also available as a search option in Firefox.
Web Developer Extension
A useful Firefox extension is Web Developer from http://chrispederick.com/work/webdeveloper/. It allows direct (via a single menu) access to clearing cookies, checking out the css styles in use, form details, image details, page outline and lots of other handy things when are trying to work out why a web page just isn't doing what you want it to do!