Expandoo expands images when they are clicked, much like a lightbox, but without opening anything new.
Expand your Twitter-Name @something in your Posting with Twitterlink http://twitter.com/something
Text expander plugin. Just like popcorn. Click and pop.
Scans posts for Youtube URLs and expands them to show a playable video at the end of the post.
Scans posts for picplz links and expands them to show the image.
Twitpic Expander scans posts for twitpic URL's and automatically expands them and shows an image.