Listen to Pandora outside US in Chrome Browser

I will take no response ability for breaking any terms of use or any other licensing!

First you need a US Proxy address, this you can buy a subscription for or pick a free web proxy from this list:
http://www.hidemyass.com/proxy-list/search-62

Of cause you can use any proxy you want, it just have to change the IP-address to a US address.
After you have found a proxy server/port you should install a proxy manager. This could be  a Chrome Extension like Proxy Switchy!
Other browsers like Firefox does have similar Plug-ins.

Proxy Switchy! can be set up to automatic switch to a specific proxy server on specific  URL's like this:

This should be saved along with the proxy profile where the IP-address and port should be.
Now just navigate to www.pandora.com and you should be good to go, but check the terms of use before initiating.