What I'm thinking is that you have an Add Image button available when you're in edit mode. When you click it, you get a small floating div with just a browse file control, description field, and submit button. You select you file, give it a name, and upload it. Tsunami automatically adds the image embedding code to your editor. The benefits will be two-fold. The ease of use will encourage people to upload images, making tsunami more media rich, adding value to the documents. Second, it encourages all images used in tsunami to be hosted by tsunami. You don't want people embedding important screenshots that are hosted on their personal web space only to have it go down. A nice version two enhancement would include the ability to browse and search existing images from this same dialog.
some permissive license goes here