I read this thread yesterday, and thought to myself, "gee, that stinks. It really is important to be careful."
Then this morning, I woke up to my girlfriend saying "uh, I think something happened to your beer..." Last night while putting a cardboard box over the ale pail (I usually do this with my carboy to keep it in the dark. With the pail it's just to save space) the box caught on the valve at the bottom and half-opened it. The whole 5.5 gallons had slowly drained out onto the floor during the night. Scratch one blonde ale (my first time ever pitching with washed yeast, and first time using whole-leaf hops), and one area rug. And now I know exactly how you feel, OP.