The website LastFM is allowing you to stream music legally for free. Every time you play a track royalties are paid to the artist so you have no reason to feel guilty. Advertising is used on the website to fund these payments. Not all full tracks are available though, and those that are you can only play three times before you are prompted to buy the track.
You can however listen for as many times as you like if you access your 'temporary internet files' folder and remove all cookies with reference to LastFM. The website Spiral Frog also provides a similar music service to people in the US and Canada however the advertising is more extensive there with users having to watch a video advertisement before playing a track.
Read this article and more at TechAce.
