I recently found a little gem in the ever-growing list of software of the Apple site. DrawBerry is a free vector graphics editor for OS X. It has a slick, Pixelmator-like interface and is pretty easy to use. It's not as powerful as Inkscape, but it's much more lightweight and it's very easy to use. Some features to note are, layers, opacity, blending modes, history, fill shapes with images, SVG support, shape alignment tool, and much more. Check out the video below, and screenshots to get a closer look.
I really liked the simplicity of the Gradient Palette: