I'm waiting for Vuzix to put out a new version of these:
http://www.vuzix.com/iwear/products_vr920.htmlThe resolution on the above is too low for my tastes (640x480 on each screen), but the idea is so tantalizing that I almost bought them in spite of that fact.
So basically, this would simulate being in the aircraft in terms of your viewpoints. You would turn your head a full 180 degrees to check your six instead of just moving your head a bit. Also, with a nVidia graphics card and the proper drivers, you will actually have depth perception. The last part is what really got me interested in them, it's called stereographics for those interested.
Other problems with these current ones is that they don't track as many axis' of movement that TrackIR does, but I'm hoping that when (if) a newer model comes out that they will add more axis'.
EDIT:
Found the new one!

Comes out in the fall, didn't realize this was going to have the ability to have 6DoF like TrackIR and stereographics! Pretty damn cool if you ask me. You also have the ability to see through the lenses if you need to... so it can actually act as a heads-up display for someone who has information they need at their fingertips.
Here's the link:
http://www.vuzix.com/iwear/products_wrap920av.html