Joshua Green has an amusing, short piece in Wired magazine on his four-week quest to become smarter, among other tactics:
Neuroscientists say that showering with your eyes closed and brushing your teeth with your "opposite" hand can open up new neural pathways by challenging your "proprioception" – your brain’s perception of movement and spatial orientation. This morning I try closing my eyes in the shower, quickly become disoriented, and wipe out. (Get a rubber bath mat, trust me.) I also find it surprisingly hard to keep my eyes shut through an entire shower. My solution: a sleep mask. It works nicely, but I look like a naked Lone Ranger.
Since I’m a sucker for easy cog science tricks like this, I just showered with my eyes closed (it was hard). I haven’t had any creative breakthroughs yet, but if I do, you better believe I’ll be wearing a sleep mask in the shower.