Open Port Indicator?

[Conrad Knauer]

I note on the sounder ML that someone (apparently) enabled Remote
Desktop and forgot about it, and someone else attempted to gain access
to their computer while they were using it:
https://lists.ubuntu.com/archives/sounder/2007-March/010122.html

Now, what concerns me is that once you enable Remote Desktop there is
no Notification Area icon indicating that its active and so it can
easily be forgotten about.

Considering the problem further, this is not just a problem of Remote
Desktop, but rather, how would the average user know if some program
they installed was listening on ports? (I suppose if they went to
Network Tools and port scanned their IP that would work, but that's
not 'at a glance' :)

Is there a program that makes a Notification Area icon to indicate if
there are non-stealthed ports?  This would be helpful as it would not
be invoked during average usage and so would be a clear indicator that
something was different.

CK