I've got several sewing kits - a big one in the desk drawer, one in my homemade PSK, one in a coat pocket, and so on.

They can be a huge morale booster. After a tough day where your job sucked, you got nothing but bills in the mail, and your dinner was bland, you can at least fix a button on your shirt or a tear in your jeans and at least say that SOMETHING went right.