I have does program once, its called TOR. It randomizes your IP almost every minute. I haven't got any problems with this program except my connection speed slowed down because of the setup of the program. You will use IP addresses of other people who are also using TOR and in return, those people will have the ability to use your IP address. It is fully automatic and the program will choose an IP address for you. The best thing is that, the IP addresses are from different countries around the globe.
Here is a link of the program:
http://tor.eff.org/
But be careful in configuring this program for it is not for beginners.