TMBG also has a super happy song called Ikea. About the store. That and Birdhouse both are supper happy-making. Others....

The Window Washer song by BNL (don't know the exact title). Not quite happy, but I love it anyway.

Love You Madly - Cake
Stick Shifts and Safety Belts - Cake
Million Dollars BNL

There's a song on the radio right now that is super happy and makes me excited every time I hear it: Say Hey by Michael Franti. Happiest. Song. Ever.