There are some short ones that will fit in the average tool box. Stapler A small, stapler that will also hold small brads can be very handy. Screwdrivers A small basic set that contains both standard flat blades as well as Phillips heads will tackle most jobs. There are some pretty neat combination drivers that include a variety of blades that all fit on one main handle. Tape Don't forget the incredible duct tape, which can hold anything together.
Electrical tape is handy too.
Drill Either cordless or electrical will do. You will also need a variety of bits. Even a small, inexpensive level can help your work come out straight. These will hold lots of things you are trying to put back together. A good, basic pair of slip-joint pliers can tighten, loosen and hold all sorts of things for you.