We're doing some advanced Wordpress templating and hacking for the new version of the awesome The Motor Report blog, and trying to do some cool things with images from posts. Rather than requiring authors to manually define "feature" images, we'd like wordpress to automatically generate various thumbnails for search results, feature post scrollers etc.
So hence, some interesting/useful resources on the subject:
Get Images Attached to a Post: Requires functions.php hacking, gets attachments from the database, rather than through brute force search of the post content.
Get the first image from the wordpress post and display it: Requires some functions.php hacking, searches the actual post text, and has the advantage of getting the first actual image in the post, rather than the first image uploaded and associated with the post.
Also interesting: Related Posts with Thumbs plugin.