Free wi-fi site survey software

[#1]

Mods: please move if inserted under incorrect topic
Ever wondered what the distribution of your wifi network looks like, or how your neighbours' may cause interference? Try this:
http://www.ekahau.com/products/heatmapper/overview.html
I know many network cards can do "site surveys" and give you an idea of what's around, but this was a revelation to me. Geek that I appear have become, I surveyed my house, using various channels. A couple of surveys are attached (I used the grid for simplicity, but you can enter a plan of your floorspace, for greater accuracy).

[#2]

I'd be a bit concerned about the apparent WEP entry on the BT Homehub. WEP is very easily crackable, so if you are actively using it then change to WPA if the router supports it, or buy a new router if it doesn't!

[#3]

I'd be a bit concerned about someone who draws all this maps and then wanders around the neighbourhood clicking their position into their laptop.
Sounds a bit like water divining.