Listen.com (owned by Real Networks and running the Rhapsody music service) is quoted in this Wired article as having doubled the number of CD track burns sold after cutting the price per track burn from $0.99 to $0.79.
Although the company has not released total numbers of burns (or the total number of subscriptions, which are required in order to purchase a track for burning), they do claim that the burn numbers are up 100% and that they streamed over 11 million songs last month (or about 350,000 songs per day).
It is important to note that the average song length is about 3 minutes 40 seconds, so we could conclude that the subscribers are listening to about 21,000 hours of streaming music per day. Not shabby, but if you start the program and leave it going over the average work day, you could consume that much music with a mere 3000 customers.
A comparison of the various music services appeared on this site earlier this year..html