Lightbox, Thickbox, Lightbox2
Yesterday, Andyman77 from the forums brought the Thickbox project to my attention. Using his plugin, I intermingled that with the existing lightbox plugin so that you can now choose which JS library to use to format your links. Plus, lightbox2 got also added to the plugin.
What, you don't know what Lightbox is? It's a nifty javascript that will transform links to images into small "popup" links. When you thus link to a thumbnail images (<a href="large.jpg"><img src="thumb.jpg" />), lightbox will take on that image link, and once clicked on it, the large image will be shown on your page instead in a separate browser window. It sounds boring when explained, so just go to the lightbox pages and look at their installations.
The plugin installation is seamless, as all image links in serendipity will get automatically rewritten so that links from thumbnails will show up as lightbox links.
Thickbox brings fun into this thing by offering to also popup HTML links inside neat popups. Just add a 'class="thickbox"' attribute to your HTML links in your entries, and that's it.