We serenade often here at Nebraska. Some fraternities Pledge educators use it for their own personal means, but most often girls will go around to all the fraternities and sing, and the guys will sing back. The other times it is done is to get your composite back from another chapter - Girls will steal the guys and vice versa, then decorate them with sexual innuendo from magazines like Maxim and such.
The other time we serenade is the Sunday before our I-week starts. It's a welcome back type of deal and also announces our Initaition party on Saturday to all the sororities.
The one thing I take pride in for my chapter is one that we're decent singers, and two that we have a lot of actual Beta songs - which IMHO is way better than something like the Righteous Brothers or any popular music. I was studying with some APhis over at their house when some SigEp pledges showed up and serenaded one of the girls for their pledge ed...and they ended up singing "Jingle Bells" I was like WTF!!!

how does that work???