iDraw is a powerful, yet easy to use, illustration and animation program for Mac OS X. It has many of the features of high-end design programs, such as smooth anti-aliased rendered paths, different fill types including semi-transparent colors and gradients, object transformations such as tapers and arcs, text shape manipulation, and much more. Best of all, it's only a fraction of the price.
ANONYMOUS this is a great vector graphics program. only reason I don't give it 5's for rating is it can be a bit quirky about a few things. A great companion for GraphicConverter. (Version 1.3.1)