The next project I am just finishing is a corner to corner afghan. It is very quick to do and looks great. Each square is four stitches and you are crocheting into the end stitch when making the following square.
In this picture you can see that after the green stripe I started on the dark blue and decided that the project had reached width I wanted. To get the length I continued increasing on one side only. This created a corner on one side, but the bottom side keeps growing.
Once I have the desired length I stop increasing and as I am following a straight edge I actually start decreasing the length of the rows until I finish back in a corner. You can also just make out in the photo that you get a nice zig-zag when you change colours. I have tried to be random with the colour changes and thrifty with the yarn, but for a cleaner look you should change the colour at the end of the row.
All that is left is to sew in the ends.
This example is long and thin as I will be using it as a chair cover.
This pattern would look great on cushions. I am considering using up scrap wool to make a scarf this way.