WIBR+ is an android app that is capable of cracking WiFi passwords. It was designed to test the security of the WPA/WPA2 PSK WiFi networks, but now it is widely being used to crack weak WiFi passwords.
It supports two types of attacks -- Dictionary Attacks, and Bruteforce Attacks. It also allows you to use custom dictionaries!
Download link:-- http://auradesign.cz/android/wibrplus.apk