I'm looking for a Indicator Menu, that replaces the notification area. Any Systray Icon should be in a Identicator Menu, because on Netbooks the Application Menus and the Systray Icons overlap sometimes
If I understand your question correctly, you are not looking for a menu but for a GNOME applet that will integrate into a panel and display these icons in an expandable menu-like view. There is no such applet that I know of, but you state that you need this in order to solve space problems on a netbook. If so, I'd suggest creating a second panel, moving the "panel notification area" (aka systray) there and setting the panel to a small size and autohide somewhere on a screen edge.
Alternatively, you could also move any other elements from your main panel there -- I generally create an auto-hiding application launcher on the right screen edge where it does not take away space and is easily reachable by "throwing" the mouse to the top right corner.