Question: Is there a way or a program that marks the icon of a file with a badge, similar to how Dropbox marks synced files with a green checkmark, and files that are currently syncing blue?

I'd use that to mark videos I've watched in a series.

Answer: 
You can try something like [**UserInfoTip**](http://www.akslab.com):

> 
> * Select some files or folders, assign icons for them, and add a description to be displayed in Explorer's popup windows.
> * You can easily notice the marked files among other files and recognize their types by the icons.
> 
> 
> 

![1](https://i.stack.imgur.com/7MMul.jpg)  

![2](https://i.stack.imgur.com/o2q6s.jpg)  

![3](https://i.stack.imgur.com/WcouI.jpg)

---

Of course, nothing prevents you from [creating an Icon Overlay Handler](http://msdn.microsoft.com/en-us/library/cc144123%28VS.85%29.aspx) of your own. You can get started by using [TortoiseSVN](http://tortoisesvn.tigris.org/ExplorerIntegration.html)'s [code](https://stackoverflow.com/questions/843506/shell-icon-overlay-c), but remember that there's [a 15 overlay limit](https://stackoverflow.com/questions/4411336/shelliconoverlayidentifiers-why-so-few) (which will get exhausted in no time if multiple programs attempt to set overlays), and icon overlays are not even recommended by people such as Raymond Chen.
You can use Rating in Windows Explorer as work around. Mark \* as read.

From File's Properties, it allows me to do file Rating from (zero star ~ 5 stars). Since I'm not using the rating feature to really rate a file, instead I use it for the purpose of marking it as a read file, no matter what file type it was. I also can sort out those read vs. unread files if I want.