I thought it would be interesting to share DC's numbers on LastFm. I think it's very impressive how good he's doing.
For those who are not familar with this, Last Fm is music community website that keeps track of the songs the users listen to on their computers or radio. It tells you how many times a singer/band/song was played by the users of Last Fm. It has more than 21 million users in many many countries and everyone can join.
Last Fm

Anyway, at this moment David has 618,758 plays scrobbled on Last.fm. David's page
Considering that his music has been available for 4 months only and his album isn't even out yet these numbers are pretty fantastic.

If you want to have an idea here are the numbers for the Idols who have the most scobbles (all the others have less than David)

Kelly Clarkson
12,708,876

Carrie Underwood
2,988,778

Daughtry
2,156,711

Chris Daughtry
1,344,925

Jordin Sparks
1,058,620

Katharine McPhee
1,033,177

Blake Lewis
651,639

And the numbers for some of the other AI7 contestions:

David Archuleta
230,357

Jason Castro
190,258

Brooke White
91,530

Michael Johns
69,502

Carly
59,085