One word: wow.
Something that is clearly overlooked within the WordPress core is thumbnails and excerpts. Not specifically the two together, but separately even.
Solution? Thumbnails for excerpts.
This is a well done plugin that I will definitely be using on a regular basis.
http://wordpress.org/extend/plugins/thumbnail-for-excerpts/
http://www.cnet.ro/wordpress/thumbnailforexcerpts/
Filed under: WordPress Plugin of the Day , Images
