My favorite songs are:

Jazz3Title.umx (Jazz3 Title song)
TubelecMix.s3m (Tubelectric song made by Tweety, Newspaz, Dreama, Blizzard, iCeD and me)
Infinity.mod (Infinity from Necros)
K_hope.s3m (Hope by Alex Brandon)
Castle.umx (Jazz3 Castle song)
Tek11bak.umx (Basement song from Jazz3)
Basement.umx (Another Jazz3 song from the Basement)
Tube.umx (Green Target)
Rocket.umx (SkyGazer)
Ascent.s3m (Ascent of the Cloud Eagle from Necros)
Click.s3m (Click from Necros)
Hgh-will.xm (Highland Willows)
m4v-fasc.it (Tangerine Fascination from Necros)
Mech8.umx/s3m (Mechanism Eight from Necros, used on UT too)
Shadowru.mod (Shadowrun by Purple Motion)
shrunsrr.xm (Shadowrun by SRRichie)
Sor-DDawn.it (The Digital Dawn by Sorath)
Sor-Genesis.it (The Genesis Factor by Sorath too)
Menu.mod (Menu from Necros used on Crusader)
Regret.mod (Regret from Necros)
Tq_serak.xm (Serakheon)
Track songs made by Purple Motion used on Death Rally game from Apogee Software
Whare.j2b (White Hare)
Woplstc.s3m (World of Plastic made by Purple Motion)
Mystic.s3m (Mysticism from Necros)
wb_takeo.xm (The Take Over II from WorkBench Project-X)
Labra.j2b (Labratory song from JJ2 made by the one and only Alexander Brandon)
Colony.j2b (JJ2 song)
Deadlock.xm (Deadlock by Elwood)
Sweetdre.xm (Sweet Dreams by Elwood)
Always.it (Always...)
M4v-univ.it (Universe Electric)
m6v-diem.it (Carpe Diem)
Repress.s3m (Repression)

And many more songs I probably forgot.