HTML cards open up a world of web power for Wagn. For a few examples including embedding a Twitter feed, chat, and video, see http://thrivable.wagn.org/wagn/HTML (we'll add some here on wagn.org Real Soon Now).
Although you can edit the HTML of any card, most complex HTML elements will be stripped out when you save. HTML cards let you add in and keep all the HTML you like. (Note that as a result of this you will probably want to restrict permissions on them.)
Cards of this type