This post is for everyone who listens to internet radio and likes free stuff.
Regardless of your music taste, and whether you've settled into your iTunes, your ForumW, your LimeWire, Pandora, or some other way of consuming music, you have to try out last.fm.
According to their website, "last.fm is a music service that learns what you love" ... and I instantly loved it back. This kind of love doesn't take a lot of effort; it's service is based not only on what you tell it now, but on your past. Meaning that for people who have been listening to music for any more than 5 days out of their lives will appreciate the seamless transition to its online/offline user experience. Borderline creepy-stalker-lover, Last.fm seems to know you as soon as you press the little "import" button on its GUI, updating your profile information to reflect your listening history. It's a good thing real relationships don't have that kind of unforgiving insight.
They also offer personalized music recommendations, some free mp3 downloads, stations based on a specific artist, all kinds of web 2.0 widgets for your blog/website/network, and automatically corrected misspellings of artist and track names. A website that can correct you, the music guru, when you're wrong???! It's creepy but it works. The question is, do you really want a service that works that well... wuahaha...