Digimon Tamers had plenty of great songs. Some only heard in the anime, like the sad but incredibly moving Saxophone with piano background version of The Biggest Dreamer, and some that were never even heard in the anime, and that (obviously) were never sold around the world.
Rika's theme from the Best Tamer album, Moon Fighter, that firmly established her as a Badass.
Pretty much any moment where the Ultimate/Mega Digimon appear is made instantly awesome by that song. It also helps that the 3 different Digimon get different renditions to start up. Gallantmon goes straight into the rock chorus of the song, MegaGargomon starts up with the rock riffs from the beginning, and Sakuyamon gets an entirely different theme (More Traditional Japanese sounding) before going into One Vision.
the German version is almost even more awesome for using the song's iconic badass guitar solo right at the beginning of the song.
The Korean Opening. Compared to the American version and Japanese version (which felt like a very typical Shonen anime opening), the tone of this version managed to capture the anime's darker theme while remaining faithful to its Shonen feel. Even better, the lyrics are all about maturity and coming-of-age, which are recurring themes of Tamers.
Say what you will about the English dub, but they nailed it with the soundtrack. In addition to the reused elements of the Digimon Adventure score, they added moody orchestral pieces that were obviously heavily inspired by The Matrix. And the theme tune gets quite an awesome remix for this season too.
The standard Digimon Tamers English Digivolution theme (heard here and here) modifies the English "Digimon Theme", giving it a nice sort of "bite" or "edge" that seems warranted for transformation scenes.