If you find yourself shooting into the sun and you need to reduce your exposure but can't, try using your sunglasses. Yup! Just put your sunglasses in front of your lens. This will reduce the amount of light by approximately 2-3 stops.
There are a few things to note about this tip though. This may not work particularly well with anything more than a point and shoot camera. The larger the lens the more likely you will see distortion in the image. By size of the lens we're not referring to the focal length but the actual physical size of the lens itself. You may also note that the image will take on the shade/color of the glass of your sunglasses. So if you wear pink shades it may not be so desirable (or maybe it is). Also, the larger your sunglasses the better off you'll be. Why? Because it means that you will be able to find a somewhat flat area to shoot through.
Lastly, what about distortion? Yes, there will be distortion. Depending on your shades, you may or may not get great results.