This is a really cool web-based annotation application. Things that they have in common with my annotation application is the need of zoom, pan, on image annotation. They have nice features like color coding and the ability to create custom annotations. They target a usability that is a bit different from what I am targeting. They use the software to handle very big images. So they have issues that I will not face: like tiling.  It’s a very good source of ideas :).  The video is posted here.