There are three different sections to Picasa's editing features: Basic Fixes, Tuning and Effects.
Picasa2's Basic Fixes are basic, but one might consider them necessities. They include Crop, Straighten, Redeye, Auto Contrast, Auto Color, and Fill Light. One unique fix is the "I'm Feeling Lucky" option which optimizes the color and contrast levels and deepens bright and dark colors with just one click.
Tuning refers to Picasa's lighting effects which allow you to manipulate the lighting in your photos by adjusting the Fill Light, Highlights, Shadows and Color Temperature.
The Effects section offers the most interesting editing options for your photos, containing Sharpen, Sepia, B&W, Film Grain, Tint, Saturation, Soft Focus & Glow. Some special effects include:
Filtered B&W. It turns your photo black and white as if you were using a colored lens filter. You choose what color filtered effect using the color picker and can see the differences in real time.
Focal B &W. It turns your photo black and white, while leaving a portion of your choice in color.
Warmify. It increases the warm tones, enhancing skintones.