I assume you’re reading this post on its own page (i.e. the permalink). If you’re on the front page, or in an RSS reader, please go to its own page.
Above the title of this post, there is the previous/next post navigation bar. Now hover your mouse on the previous post link, but don’t click :) . Did you see the little bubble showing the excerpt of the previous post? That’s it!
Sometimes title is not enough for visitors to determine whether the post is worth reading. With an excerpt, more information is provided. Some posts with great titles are worthless, while some great stories are under unromantic titles.
I just made the plugin Neighbor Post Preview to do this thing. Visit its page for download and installation instructions.
Hope you enjoy this plugin and I welcome all feedbacks and suggestions.