If you would like to blink the window title in taskbar in your web application, you need an ActiveX component, which call the FlashWindowEx API
(<DllImport ("user32.dll", EntryPoint: ="FlashWindow")> or CWnd::FlashWindowEx)
to make the window title flash.
The following link is a good article talks about Chat Application using Web services in C#, and use windows form client to make the “balloon tips”
C#: Flash Window in Taskbar via Win32 FlashWindowEx