ImageIM is a plugin for Gaim that lets buddies send screenshots to each other via HTTP. Users can simply click the ImageIM button, select a portion of the screen, and then send their buddy the image. If the buddy doesn't have ImageIM, they will receive a link pointing them to the image.
jBrout is a photo manager. It can manage albums and photos, tag photos with IPTC keywords, use internal JPEG thumbnails, add comments to photos and albums, losslessly rotate JPEG files and internal JPEG thumbnails, and use EXIF info. It uses plugins to add a variety of features such as exporting to HTML, acting like an HTTP server, and exporting to email. It works without a database, and has been tested with a collection of over 20,000 photos.