Our first solution to the "Print Diamond" kata at the first Tech Tribes Jersey Coding Dojo (http://www.techtribes.je/events/50), by Simon Brown and Jason Roberts ... it could do with some further refactoring, validation, etc but it basically works.

PrintDiamond.java

public class PrintDiamond {


    public static void main(String[] args) {
        char letter = args[0].toUpperCase().charAt(0);
        int letterAsNumber = ((int)letter - (int)'A') + 1;
        int gridSize = (letterAsNumber * 2) - 1;

        int numberOfSpacesAtEdge = (gridSize - 1) / 2;
        int numberOfSpacesInMiddle = 0;
        char letterToPrint = 'A';

        for (int line = 1; line <= gridSize; line++)
        {
            printSpaces(numberOfSpacesAtEdge);

            if (line == 1 || line == gridSize)
            {
                printLetter(letterToPrint);
            }
            else
            {
                printLetter(letterToPrint);
                numberOfSpacesInMiddle = gridSize - 2 - numberOfSpacesAtEdge - numberOfSpacesAtEdge;
                printSpaces(numberOfSpacesInMiddle);
                printLetter(letterToPrint);
            }

            printSpaces(numberOfSpacesAtEdge);

            System.out.println();

            if (line >= ((gridSize+1)/2))
            {
                numberOfSpacesAtEdge++;
                letterToPrint--;
            }
            else if (line < ((gridSize+1)/2))
            {
                numberOfSpacesAtEdge--;
                letterToPrint++;
            }
        }

    }

    private static void printLetter(char letterToPrint) {
        System.out.print(letterToPrint);
    }

    private static void printSpaces(int numberOfSpaces) {
        for (int i = 1; i <= numberOfSpaces; i++)
        {
            System.out.print(" ");
        }
    }

}