The Lonely Island is:

Andy Samberg (SNL, Hot Rod)

Jorma Taccone (SNL writer, Hot Rod)
and
Akiva Schaffer (SNL writer, directed Hot Rod)
The musical/comedy trio had been around for years and some of their skits include Awesometown. What everyone is probably most familiar with is, "Lazy Sunday" and "Dick in a Box" which are the digital shorts on SNL, almost all written by Andy, Jorma, and Akiva.
They are in the 4th season of Digital Shorts:
***=my favorites
Lettuce ***
Lazy Sunday
Young Chuck Norris
The Tangent
Close Talkers
Natalie Raps ***
Doppelgänger ***
Laser Cats! ***
My Testicles ***
Peyote ***
Andy Walking ***
Cubicle Fight
Harpoon Man
Pep Talk
Dick in a Box
Laser Cats! 2 ***
Nurse Nancy
Body Fuzion
Andy Popping Into Frame
Business Meeting *** "arcade fire!"
Dear Sister ***
Roy Rules! ***
Talking Dog
Iran So Far
Andy Punches ***
Brian Diaries
Grandkids in the Movies
The Mirror
Hero Song
Andy's Dad *** jonah hill!
Laser Cats! 3D ***
Daiquiri Girl
The Best Look in the World *** "pale stems, p-loafs!"
Japanese Office
Space Olympics
Hey! (Murray Hill)
Extreme Challenge
Ras Trent
Everyone's A Critic
Virgania Horsen's Pony Express
Jizz In My Pants Cookies ***
So, anyway, they are putting out a cd titled, "Incredibad" out February 10, 2009.
If you watched the John Malkovich SNL 2 weeks ago, or...if you're a human being with access to youtube, you've seen the video for "Jizz In My Pants" which is the new single off of "Incredibad".
I really, really, really hope they tour because I want to see them.
Here is the tracklisting for the CD:
1. Lazy Sunday
2. A Day in the Life of Natalie Portman f/ Natahlie Portman
3. Dick in a Box f/Justin Timberlake
4. Iran So Far f/ Adam Levine of Maroon 5
5. Space Olympics
6. Ras Trent
7. Jizz in My Pants
8. I'm on a Boat f/ T-Pain
9. Sax Man f/ Jack Black
10. Dream Girl f/ Norah Jones
11. Boombox f/ Jules Casablancas of The Strokes
12. Santana DVX f/ E-40
13. Who Said We're Wack
14. Punch You in the Jeans
15. We Like Sportz
16. Shrooms