You might consider XM Radio. It's not free, and they're raising the price to $13/month (from $10), but with the increased price they're giving free access to all of their 150+ stations online. If you have no interest in using it in your car, home, etc. it may not be worth it, but if you use it in other venues the online access is a nice feature. The variety's better than any other online source, e.g. they have 7 channels with different varieties of country music, 7 of soul/hip-hop/"urban", etc. I think Sirius has something similar, but I haven't used it myself.
A cool "airwave" station that streams online is KCRW, the NPR station in Santa Monica, CA. Besides the usual NPR news and talk shows, it broadcasts a number of excellent new music shows including Morning Becomes Eclectic (which has issued several CD's of artists playing live in their studio), Metropolis (great late night stuff), and a few others. Check it out at
www.kcrw.org and see if anything appeals to you. They're also introducing podcasting if you want to displace where you listen as well as when.