It seems like a millennia ago when music fans huddled around the radio to listen to Casey Kasem’s “American Top 40” or the television on Saturday mornings to see what new artists appeared on “Soul Train.”

Now, all you have to do is fire up the Internet and head over to any one of a million or two music sites like iTunes and last.fm to find new artists and “Top 40” lists that mix the familiar with the obscure.

Three such sites — SpiralFrog, We7, and The Filter — are in the news this week and each, in its own way, is working hard to introduce you to new music and entertainment content.

SpiralFrog, the free, ad-supported music download service, today announced a digital distribution agreement with EMI Music.

EMI’s catalog of digital music and videos will be available to consumers for legal downloading from SpiralFrog in North America. EMI artists are certainly recognizable — from The Beach Boys and Miles Davis to Norah Jones and Coldplay — but while your listening to old favorites it’s impossible not to stumble on indie artists and breakout bands while using the site.