I’ve just come across the CSS Property Index which is an alphabetical listing of CSS properties. Of course, there are many of these of different kinds across the web, but I’ve never found any as useful as the DevEdge Netscape Sidebar Tabs which provide Mozilla sidebars for CSS 2, CSS 2.1, HTML 4.01, XSLT 1.0 as well as DOM 2 reference and others.
The sidebars will also work under Firefox, but with several caveats. Firstly, because Firefox doesn’t implement sidebars in the same way as Mozilla, you can only view them in the sidebar if you bookmark the URL of the sidebar itself, and then check the “Load this bookmark in the sidebar” box in the bookmark’s properties window.
Secondly, because Firefox doesn’t have a sidebar-proper, you can’t just press F9 to see it, as in Mozilla – the easiest way I’ve found is to move the bookmark into your Bookmarks Toolbar Folder, so that it appears in the toolbar, within easy reach.
Thirdly and finally, the references provide a tabbed interface, which in the CSS reference, for example, breaks up the different media types properties (visual, aural, paged), and provides access to the spec TOC, and how to use selectors, except that when you click them in Firefox, they open in the main browser window instead of the sidebar, which is where they’re supposed to be.
Nevertheless, despite all these annoyances, they’ve remained in my toolbar for the past 18 months, and aren’t likely to disappear any time soon, because when it comes down to it, all you want is a quick and easy, usable, navigable link to the spec, which is exactly what these provide.