George Carlin said "I think it's the duty of the comedian to find out where the line is drawn and cross it deliberately."
eh, i just found a shield that can provide some external RAM, so is the RAM's problem solved?
MEGARAM Shield:
http://ruggedcircuits.com/html/megaram.html
I think it's also fit for us.
I also focus on drive USB WiFi dongle on USB HOST Shield.
I found a low cost usb wifi dongle, it use realtek RTL8188CUS chip
this's some spec of the chip:http://www.realtek.com.tw/products/productsView.aspx?Langid=1&PNid=21&PFid=48&Level=5&Conn=4&ProdID=274