I've found a lot of good songs on YouTube. Rather than pick out the URLs for specific songs, here are the channels I find myself going back to.
ESOLNexus -- this member has favorited HUNDREDS of videos useful for EFL teachers
icnelly -- he has many wonderful curriculum-specific songs, as well as general songs for young learners
peterweatherall -- some nice EFL songs with British flavor. Also a billion math songs that can make finding the EFL song you want a little trying.
EricHerman -- fun and funny songs. My kids go gaga for the Elephant Song.
DreamEnglish -- you can find free MP3s of many more songs at his websites,
freeabcsongs.com and
dreamenglish.comkoomakids -- "What Color is the Sky" is a great song.
supersimplesongs -- some great young learner songs, including 5 Little Monkeys and Dem Dancing Bones
I've also used these channels a few times:
freelancepuppeteers -- a former NSET wrote a song for the "let's go ---ing" units
kidsfunstuff
SesameStreet
wearebusybeavers
HarryKindergarten
EngLights
songdrops