It never fails. If I'm traveling, or even just going to spend the night somewhere other than at home, there's always something I forget. No matter how much I think I'm overpacking, no matter how brief the stay... Last time, it was my black leather belt. I was going to work the following day, and the brown belt I had happened to wear that day didn't go as well with my slacks and dress shirt as the black belt I usually wear to work. That's a really minor, harmless thing, and no one commented on the difference of course, but still, it's annoying that I can be counted on to forget something. Other likely candidates for exclusion are the power cords to recharge my phone and/or iPod.
Today, it's my e-book reader. This has nothing to do with going out, except that because I'm going out I might have a little more time in need of something to read than usual. It's just that as I was grabbing everything - let's see, change of clothes, toothbrush, spare jacket because I'm hoping to dropping the usual one off for repairs, - I failed to grab the book.
Although on the other hand, I suppose I'm lucky I've never yet forgotten my ID card to get to work. I've been here for more than a year, I use two different bags and three different coats depending on what I'm doing, I've forgotten my cell phone, cigarettes, cigarette lighter, metro pass and housekeys at one time or another, and yet on a workday I've never got further than 50 yards from my door without the card I need to get into the building.
Knock on wood.