I just wanted to thank you for posting your list of songs that make you happy- they made me happy too! I loved the songs. I have been wanting to listen to new and uplifting music and was very excited to stumble upon this page. I signed up just to be able to write you and say thanks to you and everyone who contributed 
Some of my favorite songs that make me feel good are:
Nada Surf- Always Love
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(Some other good songs from Nada Surf I like are: Inside Love; I Like What You Say; Concrete Bed)
Jack Johnson- Better Together
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Jack Johnson- Sitting, Waiting, Wishing
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Jack Johnson- Mud Football
Jack Johnson- Do You Remember
Jack Johnson- Constellations
(There are lots of good Jack Johnson songs: Never Know, Banana Pancakes, If I Could, Traffic in the Sky, Taylor, Holes to Heaven, Dreams be Dreams, Fall Line, Rodeo Clown, Sexi Plexi, The News, Walk Alone, Inaudible Melodies, etc etc etc.)
(One of my girl friends from college started listening to him a couple years ago and lately they've been helping me relax in the car on the way home from work. I always feel refreshed and lighter when i get out of the car- I think its the same way i felt listening to the songs that were posted on this page.)
Two Thirty Eight- this is an underground band that is really good. I cant choose a couple songs so I will tell you the cd's I really like:
Regulate the Chemicals & You Should Be Living
Boy Sets Fire- Requim
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Boy Sets Fire- Empire
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Boy Sets Fire- Cavity
Boy Sets Fire- 10 and Counting
Jazz June- The Medicine
Empire Day- Ice Cream on the Shoes of Empathy
I could continue, but figured this was a good start.
Hope you enjoy some of my favorites as much as i enjoyed yours.