From when MTV still showed music videos:
Summertime (1991)…DJ Jazzy Jeff & the Fresh Prince [Will Smith]
http://www.youtube.com/watch?v=X_PDns23RWY
The music starts a few seconds after the Nintendo’ish splash screen.
I had a hankering to listen to Springsteen’s *Magic *album from 2007 on the way to work – Girls in Their Summer Clothes is a song that takes The Boss’ penchant for the Wall of Sound up a couple of notches. It’s a great, wonderfully evocative summer song that didn’t get nearly enough radio airplay because of *Magic’s *opening track that railed against corporate radio, so corporate radio didn’t play much from the album.
I’ll vote for **Lazy, Hazy, Crazy Days of Summer **by Nat King Cole, c. 1964
and In the Good Old Summertime by I fergit.
I think you might be thinking of the song called “Magic”? That’s the one I first thought of when I read the OP.
Also, Elvis Costello, “The Other Side of Summer” and Joe Jackson, “Friday” even though I think it only mentions summer in the first line.
Duran Duran - Can You Taste The Summer?
And, of course, Rio by Duran Duran. 
I am the first to say Rockaway beach-Ramones.
As far as personal memories, Lonely Girl-forget by who
Groovin on a Sunday Afternoon
Vacation by the Go Gos
I wanna be a lifeguard - Blotto
Steve Miller Band says “summer” to me. Also, Lynyrd Skynyrd, for some reason. And The Hissing of Summer Lawns from Joni Mitchell.
Wild Thing by the Troggs.
Just reminds me of hanging out by the beach back in those days and listening to that flute solo echo across the boardwalk…
Country is great summer music for me, just about any upbeat country music works for me.