Who can recommend a free, easy-to-use program to make decent static chess diagrams, i.e. save them as JPG or BMP or PNG files?

Thanks!

Setup a position in Chess King and go to Menu > Export Position > Image

It's free because you already own it 

thanks I'll do that! I'm assuming they print out pretty well too?

Go to: http://chessup.net/ 

or go to here from the chess.com's Resource

http://www.chess.com/download/view/chess-diagrams-v14

http://www.chess.com/download/view/diagtransfer-301

These are really good, because you can add dots or Xs for aids in training.