Might help them better learn language. Unless you are singing Ozzy Osborne songs.
This post brought back a mostly forgotten memory-- when my oldest was a tiny tyke, after tuck-ins and bedtime stories, and before the final goodnight, I had a little ritual where I’d sing the chorus of Queen’s “We are the Champions” to him.
Didn’t help though-- he’s now a young adult, still at home, and the only things he’s a champion of (so far anyway) are video games and power-slacking 
I did. I sang “You Are My Sunshine” to my daughter every night until she was about 2. I sang “On To of Spaghetti” to my son until he was 2 as well.
I sang a slightly adapted version of “Goodnight My Someone” from The Music Man to both my kids at bedtime from infancy to around the age of two.
I made up a song to the tune of “How much is that Doggy in the window”
They liked it.
I did, but not nearly as much as I should have.
I was like that too, and turned out mostly fine, there’s hope yet.
(Or so I tell myself, looking at my son, who I’m sure could give yours a real fight at power-slacking)
All the time! I sang kid songs during the day and my favorite ballads while I was rocking them to sleep. I sang silly ditties to them at random times. This isn’t an example of good parenting, though, given my lack of vocal talent. In fact, when my older daughter was about two years old, I was pushing her in a shopping cart through the grocery store and she put her hands on my mouth and said, “Shh, Mommy, people can hear!”
People say this about my singing.
I do that, and usually change the lyrics so my child’s name is part of the song. Of course, he is probably going to grow up and learn there aren’t that many (or any) songs with his name in it and resent me for that.
Yes, I sang Eagles songs, Beatles songs, whatever I could remember the words to. When my son was 3 or 4 he used to ask me to sing the “running down the road” song. (Take It Easy.)
Every night, several times per night to kid number 2.
A lot.
It was so nice to encounter two human beings who actually thought my singing was something to enjoy.
My spouse and I each picked a song, and sang that song to both kids (twins) every night (Baby Mine and Stay Awake). We’re still doing it and they are 10-and-a-half now. We’ve had some substitutions over time, but keep returning to the original two. I only just stopped doing the anti-monster rituals. I figure we’ll miss doing these things when they won’t let us anymore, so I’ll keep it up as long as they let me.
Oh yeah. We had a bedtime ritual where the two of us would curl up in the big papasan chair in his room and I would sing to him until we both dozed off. I don’t remember at all what the songs were, but I had a regular set that I sang in a pseudo-alphabetical order (for example, the “B” song may have been a verse or two of “The Wheels on the Bus,”). I never made it past G or H before we were both conked out. My husband would come in, put my sleeping son to bed, and shake me awake to leave his room.
Almost all of my parenting was supported by advice in the mainstream child-rearing books of the day, but I believe that was the one thing most books recommended against. The theory was, if your child falls asleep with you, and then you aren’t there when they wake up, they’ll freak out.
But the books also say, trust your own instincts. I knew that for us, it was perfect. He never once awakened upset because I had left the room.
Of course, he is also the kid who Never. Stops. Talking. (He’s 25 so I don’t think he’s going to outgrow it.) He’s a great kid and all, but the nonstop employment of his vast verbal skills can be hard to take. Maybe I SHOULDN’T have sung to him so much!