I´ve been a Beatlemaniac ever since I was in my mother's womb (it's a family tradition, in fact).
Other than that, being a huge rockabilly and psychobilly fan, I should mention Mojo Nixon (not exactly a band, but still...), NekRomantix, Reverend Horton Heat, Stray Cats, Autoramas, The Meteors, and of course the classics Chuck Berry, Jerry Lee Lewis, The King, and so on and so forth.
Outside the "billy" (and the "bands"), Big Rude Jake deserves mention, and a few Brazilian artists like Chico Buarque, Bezerra da Silva, Zeca Pagodinho...
Some other assorted bands: Pedra Letícia, Velhas Virgens, Angra up to the Rebirth album (it's also a family obligation), Iron Maiden, The Who, Uriah Heep, Creedence, Smashmouth...