We have a website called www.likemywear.com, where people upload their newest clothes purchases and ask other people on the site for opinion. We have fully functional site but just need to add a feature which allows users to crop or blur their faces before submitting the image for everybody to see.
The cropping or blurring should take place after the image has been uploaded and before the image is submitted. You can take a look at the site and try submitting an image to see what I mean.
For reference you can checkout gotryiton.com to see how they are doing it. We are trying to do something similar.