Unfortunately I'm facing the wrong way to do a p2p to the nearest neighborhood (window maybe 160 degrees off?). Building is pretty much solid concrete (50 years old). Nearest house in line-of-sight from the window is closer to a mile. There's been some discussion about setting something up on the far side of the building and either running cable or setting up a repeater in the building to hit us on the far side, but it would be a big hassle.
UBNT, as another poster mentioned, makes some good wifi products. I know someone who's used a pair of Nanostations ( http://metrix.net/ubiquiti-nanostation-2-p-110.html ) to do about five miles, crossing a bay beach-to-beach. I'm sure that a mile won't be a great problem for these units. I've got one myself, they're quite worth it.
I'm sure you can figure out some sort of mount that'll fit, for example using some double-sided tape on the inside of a window.
Thanks for pointing me to UBNT. Looks like their wifi-range products are dirt cheap, but that frequency hinges so much on LOS that I don't think it can go the distance. I've got some 250mW 2.4GHZ test hardware that I set up, and it can do 300+yds with LOS but not 20m through the building.
