[ Update - A more in-depth description of the problem & the tool in this post ]
I've been working on this for a while, but the recently announced vulnerabilities in android ad networks which allow for shell command execution via hijacked traffic pushed me to release a working version before getting all the features I wanted done:
Intelligently manage your wireless on android - SWM automatically learns where you use Wi-Fi, and will turn it on when you're in one of those locations and automatically turn it off when you're not. You can also control Wi-Fi by Bluetooth association - automatically turn off Wi-Fi when you're connected to your car stereo, for example.
This is a bit of an experiment in funding open source - the app is paid in the marketplace, but also open source. If you can't, or don't wish to, buy it from the market place, you can compile it from source using Android Studio.