Some of the most stirring and epic music comes from the soundtracks of NFL Films— especially those composed by Tom Hedden, David Robidoux, and Sam Spence. Perhaps the crowning example is Spence's "The Equalizer"; listen also to the even more Crazy AwesomeDa Riffs Remix.
All of the other Fox themes have incorporated elements from the NFL theme; such as the MLB theme (still used for FSN games), and the former NASCAR variant.
NBC's Sunday Night Football theme is pretty damn epic. Not surprising considering it was composed by John Williams. The opening theme is changed every week to fit the players and sung by the lovely Faith Hill. An example. Not to mention the gratuitous Product Placement.
The background song used when SNF recaps its first batch of the day's early games is also great for getting you pumped for football.
Related to the NFL: For some reason, ESPN uses two different themes for showing NFL highlights on SportsCenter. The reason this is so inexplicable is because one of them is so awesome it sounds like it came straight out of Super Smash Bros., and the other one isn't.
Also from Monday Night Football: Johnny Pearson's "Heavy Action" (it's the theme without vocals if you're confused), borrowed from the BBC Superstars program. They don't use the original version anymore, though, but an amped-up version; Edd Kalehoff (of The Price Is Right fame) has done versions of "Heavy Action" as well.
Then there's the original MNF theme music from the '70s, a funky organ-based instrumental called "Score!"
The Super Bowl half time show used to be a great place for this having one every year between 1993 and 2004 but the one that has to top all others was the 2001 performance of "Walk This Way" by Aerosmith, they were joined by *NSYNC, Britney Spears, Mary J. Blige, and Nelly. However, after the infamous Wardrobe Malfunction in 2004, they cut back on younger female performers to prevent a repeat occurrence.
Super Bowl XXXVI. The USA is still reeling from 9/11; a memorial to those lost in the attacks goes up during U2's performance. During "Where The Streets Have No Name," Bono opens his jacket to reveal the sewn-in American flag right as he sings the line "And when I go there, I go there with you" — The implication being, "Don't worry, America. The world has your back. We'll help you get through this."
It doesn't even have to be at half time. The Super Bowl XXXIX pre-game show had Black Eyed Peas, Charlie Daniels Band, Earth Wind and Fire, John Fogerty and Gretchen Wilson perform, culminating in them all joining in on "Where Is The Love". It was much better than the actual half time show which just saw Paul McCartney sitting at a piano and singing.
Whenever you hear this music on an NFL game recap, you know it's going to be epic.
The British broadcasts of (American) football in the 1980s and early 90s had the bombastic "Holding Out For A Hero" by Bonnie Tyler as its opening music, as bodies flew into each other and balls flew through the air. Stirring stuff.
NBC Sports had a great instrumental theme in the '70s, used for its NFL coverage as well as college football, baseball, hockey, etc. It was so popular that a group called Midnite Flite turned the piece into a big disco hit called "Don't Turn Away".
Speaking of World Cup Football, beware the epicness of Vangelis' 2002 anthem, both original and remix!
"Three Lions" by The Lightning Seeds, Frank Skinner, and David Baddiel, so much so that the line "Football's Coming Home" (especially during England's Euro '96 campaign, held on English soil, and where they went out in the semi's, on penalties) can be heard at most England matches these days and the song consistently chart every World Cup, and in some cases, consign the official song to obscurity.
Before the running of the Kentucky Derby horse race, it is tradition to play the Stephen Foster song "My Old Kentucky Home." And during this, the entire crowd in the stands (which is usually well over 100,000 people) joins in and sings along. They even put the lyrics on the TV screens, so those watching at home can join in.
The Indianapolis 500 traditionally opens with the singing of "Back Home Again in Indiana". Since the early '70s this has almost always been done by actor Jim Nabors (of Gomer Pyle fame).
The old Pride FC opening theme. If the pure epic scale of that track doesn't make you want to go out and punch brick walls down with your bare fists, you may not be human, observe!
The opening theme music for ABC's Wide World of Sports. Combined with Jim McKay's narration, and you have the perfect representation of "The thrill of victory and the agony of defeat!" (Cue poor ol' Vinko Bogataj going off the ski jump...)