Wireless: Roaming

I recently purchased an eee PC 900a when I saw it on Woot ($159!!) and I have an GPS unit lying around (little hand held job without maps). So I thought one of the 900a alternative uses will be a backup GPS mapping unit/Car PC. I will be using Ubuntu Netbook Edition on the machine.

Well, one of my ideas is to have Netbook connect to my home wireless and any open wireless to grab:

1) Maps as needed
2) Radio programs (I listen to NPR)
3) Hourly News Update podcasts

So the question is, how do I set my Netbook into this mode to attach to any open wireless automatically without user intervention. I (ideally) would like it to use existing setup connections, but when those are not available and an unknown open wireless is available, it should use it. I don't see anyway to do this using the Network Manager on my current (Sony) laptop.

Also, will the wget -c option work in thy plan?

Anyone have experience setting something like this up?

Thanks in advance