Sam sings Baby in the episode "Comeback".
War sings "Why can't we be Friends?"
In episode 35 she sings Return to the sea.
bob dylan and gus and roses
episode 39.5
Yes She does ;she sings half of it like in the begging before she sings Best Of Both Worlds (ITS A VERRRRY OLD EPISODE)
bones sings in "The Wannabe in the Weeds" season 3 episode 14.
Kagome sings in chorus on episode 128.
The Master (not the Doctor) sings I can't Decide in the episode The Last of the Time Lords (series 3 episode 13).
Chandler's old girl-freind, Janice.
I assume you mean the plane episode. He sings Ready, Set, Don't Go.
She sings this song in season 1- episode 13 Hell-O to Jesse when he breaks up with her.