The application Clash of Clans Private Server Switcher allows you to connect to Clash of Clans Private Servers, made with Ultrapowa, automatically modifying your hosts file.
The list currently contains 10 servers and was created using the information shared by users on the forum ultrapowa. I remember that ultrapowa is still in Alpha, so many features on the game will not work.
You can find more information about the servers in the list on this page: http://goo.gl/cNZKuK
I remember in addition that the status of the server is not updated automatically, so if you try to log on and the game don't charge it may be possible that the server is offline. I'll try to update the list of servers as much as possible, other information can be found in the relevant section of the app.
If Clash of Clans start crashing don't worry, just go to Settings->Applications->Clash of Clans and click Delete Data, and then restart the game, this should work!
REMEMBER TO LINK THE GAME ON GOOGLE PLAY GAMES TO AVOID YOUR VILLAGE TO BE LOST!