Pandora One is the premium version of the Pandora online music streaming service.  The advantages of Pandora One include the following:

• Desktop software:  Listen to Pandora from a dedicated desktop application without the need to keep a browser window open.
• Ad Free Music: Pandora One is completely free of any sort of advertising.
• Personalized Skins: Use a custom skin with your Pandora player.
• Skip All Day Long: With the standard ad supported version of Pandora you're limited to 12 total skips per day. With Pandora One you'll be able to skip as many times per day as you'd like (note you will still be limited, due to licensing constraints, to six skips per hour).
• Extended Listening:  Listen for up to 5 hours in a row without interacting with Pandora at all.
  

This is a 3 day trial but you can get a 1 year membership if you like for $36.

INSTRUCTIONS

• On the right hand ad block there is a button for your free trial.
• Install the Pandora software if you want (not required though).
• Enjoy.