Streaming music service Slacker Radio has just unveiled a completely revamped brand, combining the best of Pandora and Spotify to challenge both.

Slacker has been around since 2006, but it has been rather slacking. Sure, it  offers a great combo of customizable radio, human DJ'd stations and on-demand streaming, but it remained far behind its rivals.

Pandora has over 175 million users, Spotify recently reached 20 million listeners and five million paying users (one million paying customers in the U.S. alone), and even Sirius XM satellite radio has roughly 24 million paid subscribers. Slacker, meanwhile, does not even ring a bell to many people, but that's about to change.

After hitting four million monthly users and 500,000 paid customers, Slacker unveiled on Wednesday, Feb. 13 a big redesign for its Web site, apps and car integrations. The basic idea is to draw mainstream users away from rivals with a "complete music service." In other words, instead of discovering a song on Pandora, search for more music by an artist on Spotify and learn more from satellite radio DJs, Slacker aims to let users do it all in one place.

With the new revamp, the company's name remains the same, but everything else is different. Slacker now looks and feels cleaner, simpler and more modern. No more dark tones and textures, and no more of the clutter that used to crowd Slacker's interface. The service now sports a clean multiplatform interface with brighter colors, simple lines and plenty of white space to add a breezy touch that's easy on the eye.

The San Diego-based company has pushed changes for its Web site, its mobile apps for iOS, Android, BlackBerry, Windows Phone and PALM, as well as its in-car apps from Ford, Chrysler, GM, Honda and other manufacturers. Moreover, Slacker also aims to strengthen its presence on home devices such as Sony, SONOS and Logitech smart TVs, and will soon make its debut on Xbox as well. And because it means business, the company has more than doubled its staff in the past eight months, and spent $5.5 million on an advertising campaign attacking rivals Pandora and Spotify.

For consumers, meanwhile, Slacker is just another choice in a sea of options. The space is already crowded and competing services are more popular, but Slacker remains confident that it can catch up and offer better services.