I added MODx to the cssFriendlyCmsList found on the
cssDiscussWiki (probably the best CSS resource available, online and onprint!). I just pasted 2 paragraphs from the MODx homepage and Features page, feel free to update the entry with more detailed infos, keeping in mind that the page is ’An overview of how easily and fully various Content Management Systems can be customised using CSS’
Another high-traffic place where MODx should be listed is the
SMForum bridges for various CMS at simplemachine.org, but there’s no wiki engine there... someone from the MODx core team should contact the webmasters