Android: AirDroid already controls your phone from any web browser, but the latest version of the app offers more useful features, like a new "find my phone" service that pinpoints your device via GPS, and complete remote control of your device's camera. Plus, it no longer requires your phone be on the same network to connect to it.
AirDroid 2 used to be in private beta, but the developers dropped the invite-only requirement to download. Even though the app isn't up at Google Play yet, you can download the APK from the link below. If you don't have an AirDroid account, you'll be prompted to create one when you download and launch the app.
You have to have GPS on for the Find My Phone feature to work accurately. You also no longer have to have your phone and your desktop on the same network to control it -- if you pair your phone and browser by scanning a QR code, you can turn off Wi-Fi and still manage your device over 3G/4G. If you want to give it a try, hit the link below for a direct download.