Resizr.com

It is so frustrating when a webpage loads slowly and often it is because of images that appear on the page and their download size. It is a recurring Learning Platform problem in schools because when teachers upload images they don't have the expertise (or the time!) to bother to reduce the image's size.
Finally, help is at hand! Read what Resizr have to say about this most useful web application:
Power users and graphic design professionals alike find image manipulation to be easy. However, for the vast majority of folks, it's not. You have to find (and usually pay) for a program, download and install it, then, you have to figure out how to USE that program. On top of all that, you have to be intimately familiar with how to use your operating system's file system. Saving files, copying files, multiple versions of files -- it's all complicated stuff for all but the most sophisticated users.