MOG will be launching a new free streaming music service tomorrow that competes directly with Spotify.  But instead of giving free users a limited number of hours per month,  as Spotify does, MOG gives each a "gas tank" filled with a specific number of free track plays for that month. While Spotify offers unlimited free streaming in the U.S. now, after a 6 months trial, usage limits drop to 10 to 20 hours. In most of Europe, the limit is 10 hours.

HOW MOG FREE WORKS:

To keep the "gas tank" full users have to be actively sharing playlists with friends on social networks, as well as, exploring and sharing MOG. The goal is to reward users with free music listening in exchange for sharing MOG virally.

Some are already skpetical of MOG's new free plan. "While we like the 'gas tank' concept," wrote Business Insider, "we wish that MOG would fill it up again at the beginning of each month in addition to rewarding you with more tracks for remaining active on the site. We think that puts MOG at a slight disadvantage to Spotify."

More details tomorrow.