Home Runs: Because We Can (Fatboy Slim), Bustin Loose (Chuck Brown), Kernkraft 400 (Zombie Nation), Off We Go--Air Force Theme (Robert Crawford), Song 2-Woo Hoo (Blur).
7th Inning Stretch: Build Me Up Buttercup (The Foundations), Rock Me Gently (Andy Kim), September (Earth Wind & Fire), Shout (Otis Day and the Knights), The Gambler (Kenny Rogers), Twist And Shout (the Beatles), YMCA (Village People), You Gotta Have Heart (Damn Yankees The Musical).
Post-game Victories: Beautiful Day (U2), Celebration (Kool and the Gang), Dancing In The Streets (Martha Reeves and the Vandelas), How Do You Like Me Now (Toby Keith), Rock and Roll Part 2 (Gary Glitter).
I suppose some nice traditional organ music is out of the question.
If I have to go with that list I'd take the Air Force Theme, You Gotta Have Heart, and Beautiful Day, though I'm probably least happy with that last one, and most of the other options for that matter. My reasoning: pop music in the ballpark -- especially played-out 1960s and 70s pop music -- has just never worked for me, probably because to make it palatable to 40,000 people teams always feel the need to go with the most middlebrow stuff possible.
Personally, I'd love to hear some salsa or hip hop music at some time other than when a Latin or African American player is coming to bat, but you never will because teams probably think it would alienate their wealthy white season ticket holders. I agree with Steinberg that in D.C. it would be awesome to hear some Bad Brains, Minor Threat, or some go-go funk -- hey, local culture! -- but you know that's not happening.
Short of that, I'd probably be most happy with show tunes, Dixieland, organ music, or anything else weird, nerdy, antiquated or quirky, which isn't the worst description of a day at the ballpark when you think about it. If I want to hear "Build Me Up Buttercup" I'll go to the supermarket.