I've used many screenshot & annotation tools over the years jumping from one to the next. Now I use mainly CloudApp for the cloud-based screenshots and SnagIt for the local screenshots. SnagIt has a lot of options but I mainly use it for its non-destructive image-editing abilities. I've not been able to find this feature in any web-based apps until now. This is mainly the reason I'm so excited about Markup Hero. Sometimes the same screenshots need to have different comments to different people or the annotations need some adjustments later on. So rather than having to take another screenshot just for this purpose, I can now go back to the original screenshot and easily edit it. As a bonus, the app has a clean UI so using it is very pleasant.