This suggestion is from a type that I've seen at the Puzzlephil site. This puzzle is called "hikaku" (the name used at Puzzlephil). It's very similar to futoshiki and greater than sudoku. You have a square grid, like a Latin square, and some of the borders between horizontally and vertically squares have indentations or "notches." These represent the inequality symbols for less than (< and greater than (>. A notch always points from a larger to a smaller number. The difference between these and greater than sudoku puzzles is that there are no 3 x 3, 9-square boxes, so they're basically Latin squares with inequality symbols added. Let me know what you think of this idea. Here's the link to the Puzzlephil site