Vector Software for Drawing and Diagramming What software is available for Mac that is good for drawing cartoons and diagrams?

These are some features it should have:


Edit any component easily after drawing it. 
Easily add and edit text anywhere. 
Graphics Tablet support, preferably with a pressure-sensitive option. 


Also it should be able to import/export:


Import other image formats, and ideally should be able to convert hand-drawn images into vector images.
Export into png and svg formats, and for extra credit, export a clickable image map.  


Extra Information:
Omnigraffle looks good for diagramming (and can export clickable image maps), but it doesn't seem like its for drawing non-diagrams.
EazyDraw looked like it might combine some graphing and drawing features, but I'm not sure how stable it is.   

What software is there that has the above drawing features and can do some diagramming?
It may be difficult to get all features into one app but I'll suggest 5. They might have features in common but I'll highlight the ones you're asking about.


Artboard - Tablet support  
Sketch - Imports/exports to SVG  
Intaglio - Diagramming  
iVinci - Converts from bitmap to vector  
Pencil - Tablet support (mostly suited for animation and cartoons with bitmap and vector drawing, onion skinning, etc.)


All of them should allow


Editing any component easily after drawing it (layer support)
Easily add and edit text anywhere (vectorized text is a standard)
Exporting to PNG (also a standard)


I can't post more than 2 links but you'll find them easily on MacUpdate (all have trial downloads).