Beat me to it, FightingIrish!

The XF-90 article at
RetroMechanix.com has both familiar and new images and primary documents on the early development of the aircraft:
The gallery has 26 images, including plans of some of the odd configurations shown earlier in this thread. Worth checking out if you are an XF-90 fan!
Also, the article is in widescreen format with fewer ads, allowing the images to load a bit faster. I'm slowly going through earlier articles and reformatting them in a similar fashion.
-Jared