Dremel Tool
Perhaps the most versatile tool in my kit, the Dremel will cut, polish, drill, sand, grind, buff, rout, and more. There are all kinds of bits and attachments available. The cordless ones are great when you need to take the tool to the project, but they do require down time for recharging, and they don't have the same amount of torque power that the Dremel with a cord has. I also have a flex shaft which is great for when I need more control over the speed of the drill. I probably overwork my little Dremel, but have never had one break down on me. I recommend you get the most powerful Dremel you can afford because you'll never wish your tool was less powerful, trust me. These tools are best for high-speed work, and you should be very careful to secure your piece before you drill it, or it can spin around and do considerable damage to you and your work. Drilling glass with a Dremel works great, but use the slowest speed possible to avoid overheating the diamond bit or the drill motor. There are other rotary tools out there that cost less, but in this case, I believe you get what you pay for.
Click this pic to go to the Dremel site for info on the original Dremel tool, and from there you can see all the cool stuff they have available. Hardware stores all carry these tools, and dozens of different accessories.
Click this pic for info on Flexshafts. This isn't the actual flex shaft I have, but it looks like a good one and gives you an idea of what the tool is and if you might like to have it on your bench. Jewelers use these, so they are built for more deliacte work than a Dremel.