Fast Picture Viewer is the first and only optimal automatic full-screen viewing utility for shooting tethered that I've found; and I've been looking around and trying out other programs exhaustively! There is one feature I would absolutely love to see, however, and that is the ability to display either an overlay or watermark of some sort on top of the image when in kiosk mode. That would make the program absolutely perfect for my needs (which involves auto-displaying photos at events instantly as they come in).
At the very least, displaying a static graphic (just in the corner, for example) would be a terrific ability to have. Even more ideally would be the ability to display a true overlay on top of each image (i.e. I could point FPV to a 4x6" transparent png file, and it would lay it over the image).
On a side-note, if anyone is aware of any work-around for accomplishing this (possibly utilizing a separate program) I'd be keen on hearing it.