Again, I just get to pick one? Sheesh. :-)
When I was a junior in college I ended up in a dormitory with the best shower ever. I want to emphasize this point. Fantastic shower. Plenty of hot water, plenty of room for your shampoo, conditioner, soap, etc. - and this shower stall just cried out for you to sing in it. I probably annoyed the heck out of everyone else on my floor, but I sang in that shower every day, all year. This shower might have been the reason that I actually passed my biology class.
I am definitely NOT a morning person, but that shower got me up and moving six days a week. (Hey, Saturdays are for sleeping in, right?)
In my sophomore year, my college did a production of Gilbert & Sullivan's The Gondoliers. A year later, I was still singing this song http://www.youtube.com/watch?v=LgJSIKhqHGE in the shower. It's been (cough) years and I still sing it in the shower. I refuse to sing it in public, (let alone while dry) but it's an awful lot of fun.