"Promotion #1

Cost: $29

Promoted plays: 1,800

New Facebook Likes: 31

Mailing List Signups: 24

Sales from Facebook Fans: $24

Sales From Email Signup: $65

Profit: $60

Promotion #2

Cost: $29

Promoted plays: 1,800

New Facebook Likes: 28

Mailing List Signups: 3

Sales from Facebook Fans: $20

Sales From Email Signup: $38

Profit: $29"

That's pretty terrific ROI I'd say. User spent $58 and got 59 FB likes (let's say those would cost $1 each to get via FB), 27 mailing list signups (let's say those would cost $2 each to get through other means), plus an actual $147 in music sales.

So the user spent $58 and got back about $260 in value.

Earbits should be pretty darn happy with that sort of ROI.