The B-52’s are perfect beach music - Rock Lobster is a given, but all of their music is great for the beach. Love Shack is another must.
California Dreamin’ ‡ The Mamas & The Papas
Livin’ Thing ‡ Electric Light Orchestra
I’m Alive ‡ Electric Light Orchestra
Xanadu ‡ Olivia Newton-John
Finale: I Go To Rio ‡ Cast Recording Boy From Oz
Downtown ‡ Petula Clark
The Girl From Ipanema** ‡** Joao Gilberto
To Sir With Love ‡ Lulu
On A Clear Day ‡ Julie Andrews
On The Boulevard ‡ The Manhattan Transfer
Fever ‡ Peggy Lee
You Are The Sunshine Of My Life ‡ Stevie Wonder
Summer In The City ‡ The Lovin’ Spoonful
In The Good Old Summertime ‡ Les Paul
Hot Fun In The Summertime ‡ Sly & the Family Stone
Vacation ‡ The Go-Go’s
Aquarius / Let The Sunshine In ‡ The 5th Dimension
Dancing In The Street ‡ The Mamas & The Papas
Up-Up And Away ‡ The 5th Dimension
Good Morning Starshine ‡ Gerome Ragni and James Rado
Put On Your Sunday Clothes ‡ Jerry Herman
Before The Parade Passes By ‡ Jerry Herman
Don’t Rain On My Parade ‡ Barbra Streisand
You Can’t Stop The Beat ‡ Marc Shaiman
Guitar Noire and Surfmania by The Aqua Velvets
Surfin’ Bird by the Trashmen
Pipeline by The Chantays
Baja by The Ventures
Big Surge and of course Wipeout by The Surfaris
Panic Button by The Bel-Airs
Finally, one cannot do the beach without Dick Dale’s Miserlou
If you would like some more serene, summer-type songs:
“Everybody’s Talkin’” by Nilsson
“On Some Faraway Beach” by Brian Eno
“Look Into the Sun” by Jethro Tull
“Towards the Sun” by Druid
This list goes to 51:
Bill Deal and the Rhondels.
I have a playlist on the iPod called ‘Beach Music’, with songs I think are beachin’.
Apache 64
Apache
The Beach Boys
Surfer Girl
Papa-Oom-Mow-Mow
Good Vibrations
Surfin’ Safari
Surfin’ U.S.A.
Big Kahuna & The Copa Cat Pack (Album)
Brian Hyland
Itst Bitsy Teenie Weenie Yellow Polka Dot Bikini
The Champs
Tequila
Dick Dale
Let’s Go Trippin’
Shake’n’Stomp
Misirlou
Mr. Peppermint Man
Surf Beat
Take It Off
King Of The Surf Guitar (vocal)
Hava Nagila
Riders In The Sky
The Wedge
Night Rider
Mr. Eliminator
The Victor
Taco Wagon
Tidal Wave
Banzai Washout
One Double One Oh! (instrumental)
Pipeline
Herb Alpert
Tijuana Taxi
Spanish Flea
Walk, Don’t Run
Zorba The Greek
A Taste Of Honey
Green Day
Last Ride In
The Mermen
Krill Slippin’
Neptune’s Revenge
Splashin’ With The Mermaid
Kaena
Over The Falls
Run Don’t Walk
Sand
The Drift
Big Day At The Bay
Hammer Head
Abalone Daze
Soul Surfin’
The Whales
By The Sea I Will Stay Forever
The Goodbye
Richie Valens
La Bamba
Santo & Johnny
Sleepwalk
The Surfaris
Wipe Out
Surfer Joe (hit version)
Scatter Shield
Murphy The Surfie
Hot Rod High
Mystic Island Drums
Point Panic
Waikiki Run
I Wanna Take A Trip To The Islands
Catch A Little Ride With Me
Burnin’ Rubber
Beat 65
Boss Barracuda
Hiawatha
Karen
Surf Scene
Surfer Joe (original version)
The Tornados
Telstar
The Ventures
La Bamba
Washington Square
Pipeline
Walk Don’t Run
Hawaii Five-O
Perfidia
Ram-Bunk-Shush
Slaughter On Tenth Avenue
Blue Moon
Lolita Ya Ya
Lullaby Of The Leaves
Diamond Head
Theme from ‘A Summer Place’
Theme from 'The Wild Angels’
The Waikikis
Endless Summer
The Girl From Impanema - Astrud Gilberto
Don’t forget Skeet Surfin’!
Of course, if you played that stuff at the beach now, the prevailing sentiment would be “Hey, let’s move away from that old fart and his dinosaur rock.” 
By sheer coincidence as I was opening this thread I was listening to the really quite good Bobby Fuller Four version of this classic.
“Hot Fun in the Summertime” - Sly & the Family Stone
Hey now, I was only in college…oh crack, it’s been almost 20 years now.
for beach sleaze: Free Men of Mauna Loa by the Honolulu Mountain Daffodils
And, of course, Rio, by Duran Duran.
Beautiful Day - U2
Boys Of Summer Don Henley
Just what’s in the playlist, Mac! 
Last Ride In, Green Day
Theme from The Endless Summer, The Ventures
A couple I mentioned earlier. They are similar tunes, and they just grab me for some reason. Thought I’d post links so that people could hear them.
.
…haha…I’m a long time beach/surf bum
…so, you want sunny blue sky music?..rough and tumbled shorebreak music?..dreary blown out? gigantic scary…? (the Mermen for that, as mentioned upthread)
heres a nice Santana one for Dawn Patrol, with a cool offshore breeze…
and then this little JJ Cale song I only heard recently…for getting the flow going…