Fix your Wi-Fi
Sometimes your phone just can't get a good connection to the local Wi-Fi network. Maybe your phone even shows you're connected but no data is moving.
There are apparently a few issues when it comes to Android and Wi-Fi and Wi-Fi Fixer works around those to make sure your phone has the best connection it can get. Better yet, developer David Van de Ven keeps this app updated and even promises new features
Wi-Fi Fixer (free).