Music streaming service Slacker has done a major relaunch, hoping to better compete with rivals such as Spotify and Pandora. The company is keeping a free-to-listen radio-style service for most customers, but also offering two paid tiers for people wanting better options. $4 per month upgrades listeners to Slacker Radio Plus, which removes ads and limits on how many songs can be skipped at a time. $10 per month gets a Premium subscription, needed for direct song access and the ability to save custom playlists.