Which tunes make you go 'ahhhh yes, sumer is on it's way!' when you hear them, or bring back memories of the sun rays dancing between the leaves of the tree you sought shade under? hehe.... ahhh...
My ones would have to be (some of them are really laughable and cheese though...)
* Justin Timberlake - Senoirita
* High Contrast - Racing Green
* Black Eyed Peas - The whole 'Bridging the Gap' album
(inparticularly 'Weekend')
and some oldy Crosby, Stills and Nash hehehehhe....
loads more but can't pin point them

silly brain.