Until yesterday, I considered Inkscape's calligraphy tool pretty useless. It was too weird and not really suited for any real work. It turns out I was wrong.
The problem with this tool was that its most useful mode - flat nib - was disabled and there was no UI to enable it. As a result, the Angle control had no effect because the "pen" was actually more of a "brush".
I fixed this, and even made the transition from flat to round a gradual one, controlled by the new Flatness control (0 = round nib, 1 = flat nib). (Actually 0 is not "round", but the pen is always rotated perpendicular to the stroke direction; any suggestions for a better term?) I also added a Thinning control which tells how much to change the width of the stroke depending on velocity (0 = uniform width, >0 makes faster strokes thinner, <1 makes faster strokes broader). I also changed the defaults of the rest of the parameters.
With these changes, the tool is now capable to do some real calligraphy. All of this screenshot was done entirely in Inkscape using a Wacom tablet:
http://inkscape.org/screenshots/gallery/inkscape-0.40-CVS-linux-calligraphy....
Other screenshots added today: tracing, text on path, tutorial, and a work screenshot from David Christian Berg. Enjoy, and don't forget to send us your screenshots!