Link to cross-browser documentation wikis.
Firstly, if you know of a more mature cross-browser wiki with a comparably permissible license I think I'll take all my stuff over there and try to bring everyone with me. The browser-independence is the additional feature which it provides, and although it is young I expect it to become one of the well-respected references. My personal vision for it is a best-practices version of the corresponding sections of W3Schools, but on a wiki.
It actually doesn't say that <b> has to be used, although it does note that it can be used. Specifically, the text says:
"The HTML <b></b> element makes all contained text bold. Note that while it is not officially deprecated, the best practice is to prefer the (more flexible) CSS font-weight property in order to separate presentation from structure."
I am slowly incorporating the recommended uses of such elements per HTML5 into the articles, but it is slow going as I am the only standards-minded editor (and pretty much the only editor of HTML articles, save some stylistic changes). Even a newbie would be valuable in this effort as I'd have someone to discuss it with and help make it easy to understand.
But, html-wise, the html&css wikia has less information, with the same kind of errors (like <b> has to be used for bolding text!) right now than in the MDN! What will it bring to link to it?
If you can ensure that there is consistent naming between the sites, the code at http://www.mediawiki.org/wiki/Extension:BADI_Pages_Created_Links (for Mediawiki but PHP source might be helpful) might be adopted for also coloring the links as blue or orange depending on whether the page at the remote site had already been created yet or not.