(I use two physically separated screens, so no flow needed.)
It's called Rainmeter, and the program itself isn't nearly as cool as the skins that people make to improve the look of the program. The program gives you local weather forecast from http://www.weather.com onto your desktop. Skins are used to include functions like newspapers (BBC), and information about your computers' performance. I started playing with it because of a giant digital clock and date feature, which I've actually stopped using (SuperColossal). You can also have your email displayed on screen, but I haven't tried that yet.You can download the original program at:
http://www.softpedia.com/get/System/Sys ... eter.shtml
Skins are at:
http://customize.org/rainmeter/skins/58074
^This is the skin that I used in the attached image. (work backwards to get to the menu)
Check it out, it's a bit overwhelming when you first get skins, due to so many options, but once you've got a handle on it, it's pretty cool.