From the Twitter account @raspipc I know a new application to monitor the state of our Raspberry Pi through Android. Their name: RPI-Simple Monitor...
The application displays information about CPU, RAM or temperature through an elegant interface.
You need to install a server program on the Pi.
I encourage everyone to try and I'm pretty sure the developer would appreciate feedback through their Twitter @laux_es or in the Google Play.
More info: GitHub - RPi-Simple-Monitor