There are many specifications that need editors. This page lists some of the more important ones. If you want to volunteer to edit one of these specs, contact firstname.lastname@example.org, post on the WHATWG mailing list or say something on IRC.
- HTML Editing APIs
- HTTP (error handling in particular)
- APNG (other image formats too maybe?)
- A specification that defines how XML maps to DOM Core. (This could be in DOM Parsing and Serialization or HTML if XML does not get updated.)
- X-Frames-Options (make part of CSP?)
- User Interaction Events (onclick, onkeypress, etc).
- Undomanager: http://rniwa.com/editing/undomanager.html and http://rniwa.com/editing/undomanager-usecases.html
- The console.* API.   
- DOM XPath
There are many specifications for extending CSS that are in need of editors. The most important ones are:
- Hit Testing (see http://lists.w3.org/Archives/Public/www-style/2010Aug/0407.html)
- Form control styling (see HTML as Custom Elements)
- Table Layout
- Replaced Content
- http://dev.w3.org/csswg/css3-content/ (Do we still want this or is the component model sufficient?)
- an imperative model of box-tree construction
Currently, the state of registries on the Web (and indeed for the Internet in general) is a disaster. At a minimum, the following registries need dramatically updating:
- MIME types
- URL schemes
It's possible that the right solution is to change approach altogether (e.g. moving more to a wiki model of registries).
See also: Registries
- an API to do syntax highlighting on <textarea>, <pre>, and contenteditable sections would be highly popular with Web developers (ack Ryan Johnson). (This would probably best be done as some sort of output filter at the CSS level, rather than anything HTML-specific.)
- Animated GIFs need a spec that, in particular, specifies how to handle timings (not all browsers honor all values, so we should specify what needs to be honored exactly)
- Client-side HTTP implementation requirements specification ("option 3" in http://email@example.com)
- innerText and outerText, if browsers don't remove them entirely
http://lists.w3.org/Archives/Public/public-html/2008Oct/0127.html has a description of some sections that needed editing in 2008 and how much work they would be.
Some notes from the HTML5 spec about things that need doing:
- a way to show icons for file types e.g. http://www.gadgetopia.com/2004/05/04/FileIconTag.html (this should probably be a function for the 'content', 'background-image' and 'list-style-image' properties in CSS)