Android: When you're asleep, at an event, or otherwise indisposed, you don't need your battery-draining data connection, but you might still want to take phone calls. Free Android app APNDroid can selectively turn off your data access while allowing calls.
The app's design is a clever one, as activating APNdroid from its app button simply activates the on/off switch for GPRS, EDGE and 3G networks, allowing you to use the APNDdroid icon as a kind of widget on your Android screens. You obviously won't be able to surf the web or sync Google services while your data services are off, or send MMS messages. You will, however, have basic phone functionality, and your battery will probably live a bit longer without having to keep a data antenna powered at all times. If you need a quick fix but want to keep cellular data services off, you can still switch on Wi-Fi to sync or send an important message.
If they could only make a plug-in so data could be turned on and off by the Locale app, we'd be living in the age of total Android control.
APNdroid is a free download for Android phones only. Be sure to note the developer's warning: If you're going to uninstall APNdroid, do it while your data services are on, or else the fake/non-existent Access Point Name the app uses to kill data will stick, and you'll have to manually switch it back.