App: MopiShape
Developer: NOKKEUSI Inc.
Genres: Developer Tools, Graphics & Design

MopiShape is a vector drawing app using bezier lines. 

It is suited for making a relatively small illustration such as icon, 
not recommended for a large poster.
But you may enjoy the simple vector based drawing with it.

Different from paint brush like apps which use pen or brushes to draw lines, 
MopiShape defines lines using several points such as start point, end point and curve control points, etc. It makes easier for you to adjust lines. 
You can try until you satisfy for your work. 

Although you may be puzzled at first time, you will get used to it soon 
and you will be able to draw interesting works easily. 

When completed your work, you may export final image to common image format files. MopiShape can write tiff, png, jpeg, gif and windows bmp format. 
You can use your own art works on your homepage, greeting cards, poster, etc. 

Enjoy drawing with MopiShape. 

Drawings are saved with the MopiShape's file format. OS X Lion's autosave feature keeps your work always saved. If necessary, you can revert to the older version image easily. 

Notice!: 
This app is suitable for mouse I believe.  I have recommended to use mouse for this app.  
However, to tell the truce, I have been trying to use Magic TrackPad.  It would be better change the settings of track pad to use three finger drag gesture, if you are a magic track pad user.

For developpers… 
If you are an App developper, MopiShape is useful to draw your icons. Because the image generated by MopiShape is scalable to exporting image size.
MopiShape's Cow icon itself is drawn with MopiShape.

Release notes:
Bug fix
"The export image size list in the preferences dialog is not saved" is fixed.