Wifi Inspector for Android. A great app for those who care about who else is on your Internet traffic and steals it quiet. The app allows you to discover all the devices connected to your network in less than a minute.
Features:

• Fast search and displays a list of devices connected to WiFi networks or 3G (consoles, TVs, computers, tablets, phones, etc.)
• Display available information about the connected device: IP address, device manufacturer, device name, MAC address.
• save a list of unknown devices.
• Rename in the list of unknown devices.