Inplace_preview is the first. It monkeypatches Scriptaculous‘ InPlaceEditor to give it a preview mode. It also includes an ability to do an ajax call for rendering the preview. It comes in handy when using an InPlaceEditor for editing HTML but with the ajax rendering anything would be possible.
Here’s an example (if you save you’ll get a big-ol error since we don’t actually save here):
Click Here to Edit…
Here’s an example: