Two tools that have upgraded my capabilities, much beyond my skiill level.
1) Kreg pocket hole system. For the money, it is at the top of my best values.
2) I struggled a long time with the decision whether to purchase a Festool Multi-Function Table (MFT) when I bought their circular saw. After using the MFT for only a few months, it is number two on my list in terms of best value. My shop is very small and my workbench has limited ability to clamp and hold pieces firmly. The MFT has solved this problem for me plus providing a nice flat area for working. It may not have as much value to others with nicer workbenches and larger shops but more me it is now the heart of my shop. The quality of my work has improved an order of magnitude at least. The other Festool tools are nice but this is the best for me.