Two of the heavyweights of Ad-Supported digital music have announced performance metrics. Spiral Frog have reached 1 million unique monthly visitors and 400,000 members. These are solid stats and represent a 5 time growth in UV since launch month. On a somewhat larger scale imeem has hit 20 million unique monthly visitors and reports 65 thousand new registered users daily. A straight comparison between the two sites isn’t of course wholly fair as the two are very different propositions and imeem has been going for a good deal longer. Meanwhile Qtrax, label licenses not withstanding, have announced approximately 300 thousand unique visitors to their site following their launch. The key take away, is that Ad-Supported adoption already has solid momentum just one month into 2008, the ‘Year of Free’ TM lest you forget.