Variety of the freebees, drill bits, some tool bags, a couple hand held grinders (so cheap I have two so I don't have to bother changing the stones or brushes), their tool that uses vibration for cutting, a 1x30 belt sander, etc.
I bought the vibration cutting tool when I installed some wood flooring to cut under door jams, etc. I have found it more useful than I anticipated. It will often work in corners or tight spots when nothing else does. Handy to have if you do handyman work around the house and garage. The other thing I will note is that I acquired some belts for using my 1x30 belt sander to sharpen knives and tools. A friend who is an avid outdoors man put me on to doing this. It is really worth doing, especially if you already have the belt sander. Very short learning curve, by far the easiest method I have ever used to get razor sharp results. You can buy the belts on amazon, ebay, etc. My friend gave me a couple very fine grit belts (1000 - 2000) to get me started. His source is a company on the internet - tru-grit.com, but he also buys other knife making supplies from them. I don't have the leather stropping belt and compound he has to finish off a blade, but it will happen when the belts I have need replacing. You can get razor blade results with the 2000 grit belt, but the leather stropping belt puts a beautiful polished finish on the cutting edge.