eMusic has been around since 2003 and they have just surpassed the 250 million downloads mark today, showing that there are other music providers out there besides iTunes that have made a significant impact.
eMusic is an online subscription-based music store. It offers up MP3s that are unprotected and will work with both Apple and Microsoft players. The difference from other services here is that they use a subscription model. This means you are guaranteed a given number of songs per month at a particular rate. This actually works out to be cheaper than the $.99/song over at iTunes.
Independent labels are represented more than major ones and their catalog is small with just 4.5 million song offerings. Good for eMusic for hitting this milestone!