If you are talking about the first song in this link…
http://www.youtube.com/watch?v=uRv4CoXQoAQ

It’s Nobody But Me_The Human Beinz
http://www.youtube.com/watch?v=nxtJoGdujYo

If that’s not it and you find a sample post it.

Look here:
http://www.squidoo.com/yes-man

The first song in the trailer is Nobody But Me by Human Beinz (http://www.youtube.com/watch?v=nxtJoGdujYo)

The second song is Won’t Get Fooled Again by The Who (http://www.youtube.com/watch?v=Rp6-wG5LLqE)

The third song is Pork and Beans by Weezer (http://www.youtube.com/watch?v=WanLLnVixC4)

There are also 48 songs in the movie itself. In fact it has a really, really good soundtrack. The soundtrack album only has 13 songs, but you can find the videos and downloads for all the songs here:

http://www.reelsoundtrack.com/index.php?act=movie_details&id=52756

Here’s the complete list of songs from Yes Man:

A Little Bit Of Basie by Red Garland
A Reunion Of Friends by John Williams
Ana Ng by They Might Be Giants
Animal by Eels
Blinking Lights (For You) by Eels
Bus Stop Boxer by Eels
Can’t Buy Me Love by Jim Carrey and Zooey Deschanel
Carry On by Jean Knight
Cool Jerk by The Go by Go’s
El B’Nia by Maghrebika
Emperor Waltz by Lawrence Welk
Eyes Down by Eels
Flyswatter by Eels
F*ck This Sh*t by Charlie Clouser
Helicopter by Bloc Party
Hyper Enough by Superchunk
In A Jar by Dinosaur Jr
Journey To The Center Of The Earth by Von Iva and Zooey Deschanel
Jumper by Jim Carrey
Keystar by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
Lazer Gun by Norwood Cheek and Peyton Reed
Leaving Hogwarts by John Williams
Let’s Get Small by Trouble Funk
Man Up by Eels
Mr. Touchdown, U.S.A. by William Katz, Gene Piller and Ruth Roberts
Old Enough by The Raconteurs
Olde Mill Inn by Blackmore’s Night
Original music for Yes Man by Lyle Workman and Mark Oliver Everett
Prologue by John Williams
Separate Ways (Worlds Apart) by Journey
Somebody Loves You by Eels
Star Spangled Banner by Zooey Deschanel
Staring At The Rude Bois by Gallows
Stomp! by The Brothers Johnson
Sweet Ballad by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
Swollen Summer by The Bravery
The Good Old Days by Eels
The Sound Of Fear by Eels
The Spaces Between by Expatriate
Theme From Blinking Lights by Eels
To Lick Your Boots by Eels
Uh by Huh by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
Umbrellas To Mend by Frisco Jass Band
Water Music by Aradia Ensemble
Wooden Nickels by Eels
Yes Man by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
Yes To You by Alice Faye
Your Lucky Day In Hell by Eels