Nail Board, Bush Hook, a good hand axe, most tools you find in the hardware store can be improvised weapons. I have a family friend who loves to use a good sized PipeWrench as a weapon over anything else.
Now my personal favorite is the Maglite 5-Cell D model flashlight which is good for bashing the head of any assailant trying to sneak up behind me in the dark.... I go out at night most of the time and I always keep that flashlight in my car seat. Just another idea.