Dabbleboard is an online whiteboard that will allow you and your MIA students to share a screen, and collaborate in real-time. Start by going to http://www.dabbleboard.com and start a drawing. (No account is needed, unless you want to save your work online.) Customize a URL for your page (or you can use the one that's generated for you), and post it, or email it to your students. When they log on, they will be able to see what you do on the board, and can participate in the written chat, or even via voice/video chat. Your sniffling students can demonstrate their problem-solving skills, for example, without ever leaving the comfort of their homes, and you have the satisfaction of knowing that you won't have to play an extended game of "catch-up" when your students are well enough to return. You can insert documents and images, and use the freehand drawing tools to create create diagrams and mind-maps.
Give Dabbleboard a try below, and then try it out with your class. Yes, it may take a little planning to make sure your students are logged in to the right place at the right time, but I really think you'll find this worth the effort.
Oh, and now that the cold weather is on my mind, I have to share a fun weather website: YoWindow.com. If you start your school day by looking at and/or discussing the weather, or if perhaps you have your students graph weather data, you will definitely want to check out this site. Not only will you get the usual temperature and humidity information, but it will be displayed on an animated background. Take the time to customize, and add the widget to your website or wiki, and be sure to view it full screen. Studying another country, or communicating with pen pals? Create a widget to show their weather too!