http://www.eslteachertalk.com/2006/0...the-classroom/ 
I think singing songs can be fun but sort of like I said before, there needs to be a point. Why are you singing? Why did you choose that song? Should they actually sing the song? Should they be trying to understand the lyrics?
There's a site called flocabulary where they teach English through hiphop lyrics. Goes to show there are people out there doing all kinds of stuff with music. Basically, if you are excited about it and believe it to be helpful, it probably will be exciting and helpful.
Students will ride your momentum.