Rounded Corner Image Maker
Note that many modern web browsers now support the CSS border-radius property which can produce this effect using CSS only, without requiring any image files - you should use this approach if you can.
This utility can be used to generate a set of 4 images, of the size and colour you specify, that can be used to create boxes with rounded corners, commonly seen on websites.
Pick the foreground and background colours you want to use, enter a radius value (higher values give a more gradual rounding) and click 'Go'. The 'Preview' link will take you to an automatically generated page using the images that you have created.