There are two ways to freeze action on your camera's sensor. You can use a really fast shutter, or....you can go even faster! For an iconic water droplet shot, you can use your flash as the key light, effectively making the flash's pulse the speed of the shutter. This was one of my first little projects. I prefocused my camera on a certain spot, turned out the lights to create pure darkness, and dropped water into a pan while firing away on the camera/flash. It takes a lot of shots, but you can get some pretty cool results. The different water colors are actually reflections from various objects (books/tshirts) that I put next to the water. The setup I used is shown below. There are plenty of guides online, including: http://www.diyphotography.net/the-comprehensive-water-drop-photography-guide/ so try it out!
I took these shots a long time ago in JPEG. I'm always looking for more cool indoor photo ideas that will help my technical skills, so if you have any suggestions, let me know!