The mental image of the Hypnotism Tuba is hilarious.
So, songs:
Dies Irae: https://www.youtube.com/watch?v=Dlr90NLDp-0
It's a song about the Christian apocalypse, sung at funerals, and kind of a poster song for Ominous Latin Chanting, so I'd say it would cause a widespread fear effect among enemies. If given enough power, it could probably even kill.
Another option would be for it to be a musical Penance Stare, forcing people to confront their sins. After all, it's a song about judgement.
O Fortuna: https://www.youtube.com/watch?v=BNWpZ-YKvU
The song is about Fate (and another poster song for Ominous Latin Chanting), so I'd say it could focus on manipulating luck, perhaps like an Entropy Curse from the Dresden Files (which manipulates luck so that the target dies).
Bonnie Ship the Diamond: https://www.youtube.com/watch?v=bk2nIrZV-9w
And now for something completely different. This song is a sea chantey and would have power over large bodies of water. It would probably act mostly as a counterspell against storms and so on.
Night Train: https://www.youtube.com/watch?v=gPFZgeCtfag (the video I chose is a Muppet Show performance of it, so please subtract the gibberish speaking and the explosions).
This Jazz hit does what its name suggests- it summons a magical train (tracks included).
The Pink Panther Theme: https://www.youtube.com/watch?v=9OPc7MRm4Y8
As well as being iconic, it would be a good choice for being able to conjure various crystals (the Pink Panther is a diamond)
Simple Gifts: https://www.youtube.com/watch?v=CLAnuG1340g
This song might work as a general counterspell.
House of the Rising Sun: https://www.youtube.com/watch?v=hzc20VmMCl8
This would induce paralysis.
Carnival of the Animals: https://www.youtube.com/watch?v=wBGEf4urGNo
Each movement would summon the animals associated with it (lions, chickens, donkeys, elephants, kangaroos, fish, people with long ears [not kidding, this is actually a movement], Cuckoos, birds in general, pianists [be careful, they may not like being summoned], fossils [animated ones], swans, and, if the player is a Disney fan, the conclusion summons flamingos with yo-yos)
Swing Low, Sweet Chariot: https://www.youtube.com/watch?v=v8frEt6w4G8
Teleportation.
Scarborough Fair: <a href="https://www.youtube.com/watch?v=wiZJPXLmrQ">https://www.youtube.com/watch?v=wiZJP_XLmrQ
Sets a task that must be accomplished by anyone who wants to do a certain thing (say, get into a secure facility, or attack you). The task can be anything, and as impossible as you want it to be. You could say 'you must walk on the moon before you enter this room' or just' 'before you enter this room, you must walk twenty steps on your hands'.
I Gave My Love A Cherry: https://www.youtube.com/watch?v=OORxUZP2Ez4
Like Scarborough Fair, but with riddles. The victim must solve the riddle before being able to do something, a bad effect tends to happen if they get it wrong. The riddle must, however, have a solution. Otherwise, it's not a riddle- just a collection of gibberish.