Is it possible to establish a wireless bridge between 2 houses, even if there's some other houses and trees obstructing the direct Line of Sight of the 2 building?? If it is possible, what do I need then?
If the signal have to go through the building and the tree, what do I need then?
What equipment will I eventually need?
A leased satellite channel?
Seriously, you can try various things, including signal amps (boosters) and dish antennas, but in the end, this wireless technology is a local area technology. It is not intended for long-distance broadcast.
Of course, you could invest in commercial equipment being used by various companies (and, regretably, some cities) to deploy metro-wide wifi, but that equipment is a bit pricey.
The comment about the satellite was intended as a joke... (sorry for my dumb humor...)
Anyway, how far apart are the houses?
Can you get to the roof of both houses? (Preferably with an ethernet cable.)
If you can get to the roof of both, would that allow you to get clear of some or all of the other houses?
There are plans you can find on the internet to make home-built high gain antennas out of simple materials (such as tin cans). But, depending on the answers to the above questions, it may be hopeless anyway.
I doubt you will be able to bridge across 1150 feet (for the metric impaired) with several buildings and other physical obstructions in the way, at least not without spending some serious money.
If all you want to do is share data, you might want to look at some of the online data storage services. Some of them provide modest amounts of online storage nearly free. They can act like a WAN-based LAS device. Supposedly, they are secure (but caveat emptor; I've never used them).
Or they could setup a ftp server. But there uplink speed will still be their governing factor for speed. So that part will not change.
All you need is a OLD PC the install WarFTP or look at the FreeNAS they have added FTP access to it. Then just point your router to redirect port 21 to it. Get a DYNDNS domian name if you do not have a static IP.
The only reason why I wanted to share my connection was, that my friend doesn't have the money it takes to establish a ADSL-connection...
You know, here in Denmark it's pretty expensive to have internet connections, compared to Sweden.