This MetaFilter script shows profile pictures of registered users (if any) in their posts to the left of the "posted by" text. The image is a 64x64 size thumbnail, but if you hover over the thumb, it will expand to a 256x256 image.
The script gives each image 1.4 seconds to load as it goes down the message list. Extended server or connection delays may cause images not to load unless they are already cached in the browser (i.e. previously loaded).
Starting with version 2.0 a placeholder image is shown for users without a profile picture, or whose picture has taken longer than the default 1.4 second load time to appear.
Fixed a bug where the script didn't always work on all pages at all times.