We went to a free demo Music Together class & it was awesome. I can't afford to sign DS up but if it's not too pricey for you, give it a try! We also look up songs on youtube, DS will say he wants a song about a cat so I try to find cat songs, for ex. We get a lot of poor-quality songs that way but a lot of great ones too (and we don't watch the videos, just listen, the videos often creep me out).
Sooo... We sing Wheels on the Bus, Twinkle Twinkle, Farmer in the Dell, Renee & Jeremy songs (It's a Big World Baby, We Are One, C'mon C'mon), Raffi (Baby Beluga, Brush Your Teeth, etc.), Itsy Bitsy Spider, Old Macdonald, The Cat Came Back (a horribly butchered version lol), She'll Be Coming 'Round the Mountain, Five Little Monkeys, Six Little Ducks, modified versions of The Elephant Song & The Duck Song (youtube), ABCs, Alphabet Sounds (Barbara Milne on youtube), Ring Around the Rosy, Frère Jacques, This Old Man, Baa Baa Black Sheep, Three Blind Mice, Open Shut Them, Head Shoulders Knees & Toes, wow I guess we sing a lot (too bad I can barely carry a tune!!), I can't think of others at the moment but we sing most of those every day. We also make up songs, we have a song about Daddy flying in a big red airplane (and a yellow dump truck, and a little red racecar, etc.) that's kind of to the tune of Great Green Gobs of Greasy Grimy Gopher Guts lol...