I always sing in the lab. Not just singing, I dance too. Believe it or not. Luckily my PI enjoys when i do that too.
For me those things fill lot of energy in the lab.

Pradobh, that's awesome :) I love having music going in the lab, but usually that usually requires iPod listening-which I feel often creates a barrier to lab socialization/community (it's OK when I seriously don't want to be bothered). My current lab is an open format, and my section is far too reserved. Grad lab we didn't have generally have music on because it had previously been used as a weapon of personality warfare. We did crank up some tunes when the lab was sparsely populated... and when we had lab cleanup days, which made things more fun-specially when a male grad student starts serenading your male PI with "you make me feel like a natural woman".

AmoebaMike, glad you and your wife enjoyed it. I personally think we need more stuff like this. It provides much needed evidence that scientists have real personalities too :)

GR, violin is a new one (in the sciences, at least). I really enjoyed choir and piano, but transporting a several hundred pound upright around the country and trying to squeeze up stairs and into a small apartment wasn't really feasible. I had friends in grad school who played flute and french horn.

Here is something I wrote about dancing in the lab.
http://scilive.blogspot.com/2010/09/dancing-in-lab.html
May not be great. But its my expresison.