ImgLikeOpera is a Firefox addon, allows load only the images that you want in Firefox browser.
Features: placeholders for blocked images (hi, LJ treads), (re)load image from context menu or Ctrl+rightMouseClick, forced expiration time (5 minutes - 3 months), policies for tabs, and filters.

The license of this software is Freeware, you can free download and free use this browser plug-ins software.