I've tried this with one house in between and it didn't work. Since then I've discovered the wireless kit that is sold in this country is limited to prevent it causing too much interference with other houses. You're best bet is to try get something which you can put DDWRT
on. This will give you options to increase the output of the wireless router (this is technically illegal and may also damage the router). You can then try use a directional antenna to boost the strength again which will prevent the rest of house 2 getting the signal from the router but might be enough to get it to house 6. Allegedly you can make one of these out of a pringles can if you like but you can also pick them up cheap on dealextreme.com. Also you may need to talk to the houses in between to find which wireless channels they are using and to avoid them as best as possible (they overlap so the further away numerically the better).
If all the houses were on the same power circuit you could try using a homeplug connection but that is probably unlikely to work.
Ultimately If you want this for anything other than basic internet access you'd be lucky to get anything usable from it though. Streaming or file sharing will probably never work at those distances without some major kit. Run a cat 5 cable across the roof is your best bet.