title: Mark areas over an image with javascript
body: <p>my problem is: I have an image and want to mark some areas over it and store the coordinates. Something like tagging someone in a photo on facebook. The user should be able to mark squares and polygons.</p>
  
  <p>Someone knows any library that could help me to do this? May be something in jquery.</p>
  
  <p>tks!</p>