Android/Windows/Mac: Open Garden is both a Wi-Fi tethering app and a mesh network. Install it on your Android phone and you can use your mobile data wirelessly on your Windows or Mac laptop, as well as Android tablets. Not only that -- you can piggyback on other people's mobile connections.
Once you've installed the app on your phone and the client on your computer, Open Garden will run in the background managing the connection over Bluetooth.
The Android app shows you all the devices connected in Open Garden, as well as the data being transferred. Open Garden supposedly sniffs around for other devices using Open Garden and will manage the best way for yours to get online.
Right now, there's no control over who you're sharing your data access with, though later versions of the app will provide for that, how much data you want to share, and the ability to consolidate two different network's streams for faster surfing (which would be really neat).
I connected my Android phone to my Mac with Open Garden and was able to surf without Wi-Fi, but I didn't see any other Open Garden users in my area. The app was a little finicky to get the connection up -- I discovered that it's best to fire up the Android app and then reopen the program on the computer to kickstart the connection, even though it's supposed to do this automatically.
There are many Android tethering app options, including our favourite PdaNet, but Open Garden really has potential for expanding internet access availability wherever you are.