wmd ftw!
Comment forms that don't provide previews — or at least an indication of how comments are processed — really annoy me. If I decide to leave a comment I take care to avoid spelling mistakes and grammatical errors. It's quite upsetting, then, to see my code snippet completely mangled and my carefully typed links displayed in plain text (<a href="…).
Despite my appreciation of the preview, not one of my sites provided this service until a few hours ago. Now that I've migrated from WordPress to Mango I'm able to spend some time working on front-end code. My first two challenges were localizing dates and times, and integrating wmd.
Getting wmd working turned out to be extremely easy, but I was not content with a live preview of the comment only. No, I wanted the preview to resemble as closely as possible the published result, which meant updating the preview area in response to changes to "name", "e-mail", and "website" as well as to changes to the comment itself.
This was a great deal of fun to implement!