Title should say all, but here's some network topology:
Laptop(s), desktop(s) <-wlan/lan-> router <-wifi-> android <-internet->
So I'd walk into the reach of my wifi and my android would connect to the wlan automatically and voila, internet for the rest of the network.
I think this is a good approach https://help.ubuntu.com/community/Internet/ConnectionSharing and I'll probably figure the rest out myself before long, but if someone who knows what they are talking about could create a better guide or even an app for android for this, it would be much appreciated.
As for the use of this. e.g. range, network resilience (when used in mesh networking).