Alias, formerly Alias|Wavefront, now owned by SGI (although in the process of being acquired by management) has released SketchBook Pro, a sketching program for free-hand artists. The software has been available for Windows for about a year, but Alias has decided to make it available to Macintosh users. Basically, it is a simple sketch program with some pretty advanced features and very sophisticated pen support for tablets.
Among the cool features is the built-in Mail support which will convert the drawing to one of a variety of file types before sending it.
14-day demonstration copies are available from the company's web site.