I'm a diehard flight simmer - I use X-Plane a lot, but lately have been using Outerra most of the time just because the visuals are so much better (and it does a true cylindrical projection, which X-Plane can't - I have a large 180 deg cylindrical screen).
I often use the HUD in Outerra (brought up with tab) to give me an indication of speed, attitude, and altitude. I wonder how difficult it would be to add a flight path vector to this HUD? Some examples from a quick Google search:
I thought I saw mention on the forums somewhere something about flight path, so maybe Outerra is already doing the math behind the scenes for this, it just needs to be displayed.
This would be pretty sweet when flying the Mig at very high angles of attack.