Oddly enough, I suggested something similar to Eye-Fi when I was talking to their engineer yesterday. They could include a sleeve or attachment for the SD card that would, as you posited, extend the card's range.
I may well experiment with your excellent suggestion. I already own an 8 GB Eye-Fi X2 Pro card and would love to use it for image transfer to my laptop computer at certain events. It would be cheaper than a Nikon WT-4 Wireless Transmitter by an order of magnitude.
============================================== Darrell Young (DigitalDarrell) www.pictureandpen.com "Better too many words than not enough understanding." ==============================================