This is my hack at the Utah teapot, fiddled so that it will actually print on a RepRap with no support material. I had to fill in the inside of the lid to do this, and the inside of the top of the teapot gets a bit gnarly as I increased the wall thickness there in a rather rustic manner. I also took a few liberties with the line of the spout and managed to beat the overhang problem in the end.
Printed in 0.47mm layers, 0.7mm extrusion in PLA with homing on. It needs tightening up a little to be waterproof, and the handle will need to be thickened to take the weight of a full pot.