Here are some of the cool things users of my Edison tool (the Think, Try, Learn experimenter's journal) are experimenting with. Is there anything you've been thinking of trying out? Go for it! Thanks, everyone.
Health and diet
I've joined Rofellos in keeping a food log. His is at Effect of Keeping Food Log on Nutritional Behavior and mine is keep a simple food log for the next few weeks.
In Legumes and Body Comp, Rainman03 is, for 21 days, eating legumes with most meals to see if it will affect weight and body composition.
Chad Fowler, in Slow Carb Diet, is following Tim Ferriss's Slow Carb Diet from The 4-Hour Body: An Uncommon Guide to Rapid Fat-Loss, Incredible Sex, and Becoming Superhuman (a typically Ferriss provocative title) including weekly binge day, AKA a cheat day. (Interestingly, Rofellos is doing something similar above with his "skip" day.)
In keep feet warm while mountain biking in winter I'm experimenting with different footwear solutions. Andrew suggested Ski Boot Heaters, which kicked off a little search where I found this MTBR thread and the Hotronic FootWarmer. I decided the relatively low-tech Pearl iZUMi Barrier Cycling Shoe Cover along with Seal Skinz and SmartWool socks like these. The combo has worked well so far in as low as ~30 degree F weather.
Syler is Implementing the GTD System and Its Effect on Mood, which, wearing my time management hat, is exciting because she's actually testing David Allen's claim of "stress-free productivity" in his book, Getting Things Done (highly recommended).
Ralf Westphal experimented with Make my office paperless and ended up adopting it permanently, based on such a positive result (he says "I never need to worry about whether to throw away of keep some paper.")
David Guzman is keeping track of Lessons Learned during his volunteer work, something I've found value in (see Some thoughts from tracking "lessons learned" for a year) and reported on the last two years in Personal Lessons Learned in 2008 - The Intersection of Past, Present, and Future and Lessons Learned for 2009. Unfinished Business, Only the Best, and You Never Know.
As a one-time "micro experiment" I tried cooking blackened salmon. It was a smoky mess, but tasted great.
Finally, as a nice example of a an experiment apparently in an actual science lab, sonicity asks, Does a small flask give me enough cells for plating?
James Bishop is Washing dishes with rubber gloves to test getting rid of a rash.