One of the coolest effects (and one of the oldest) ever is slow motion. The drama you can create with this effect is awesome and where would the shampoo industry be without it? Some filmmakers like John Woo and Brian DePalma have used this technique ad nauseum, but if you need it, it's good to have around.
Most editing programs will let you slow down your footage in post, but it never looks very good. If you plan ahead and shoot with certain camera settings, it will look great. All you need is a camera that will shoot in 60i (60 frames per second, interlaced) and allow you to adjust the shutter speed. You'll also need a beefier editor that will let you use the Double NTSC (59.940) frame rate. In this example, I'm using my trusty editing software, Sony Vegas Pro.
Links mentioned in the above video:
Download the Lagarith Lossless Video Codec:
Eugenia's original "Butter-Smooth Slow Motion" post:
Download a FREE trial of Sony Vegas Pro 10: