Following in line with reports a year ago that NBC's free episode streaming resulted in higher TV ratings, as well as Chris Anderson's recent buzzed-about Wired cover story on the power of "free," Last.fm is announcing that its three-month-old, full-track music streaming service is actually stimulating more business through its affiliate programs with Amazon. From paidContent's post on the announcement:

Some of that is attributable to an expected increase in site users following the new offering - but Last.fm also claims those who were members prior to the launch have been purchasing 66 percent more albums and tracks than beforehand, thanks to the full new previews. Figures for Last.fm’s 7Digital and iTunes affiliates weren’t disclosed and Last.fm wouldn’t supply the baseline figures.

Co-founder Martin Stiksel (via emailed release) offers the stats as evidence free music discovery can lead to dollars: “In just over two months, it’s become clear that people will buy CDs and downloads if they get access to the kind of service we offer.” That may help reassure some music execs that services like his, imeem and iLike can indeed aide sales.

I think there's something to this. I buys tons of music on iTunes after discovering bands on Last.fm.