Looking for javascript-based CAPTCHA code

You know, the best kind of CAPTCHA I've implemented is one that's invisible to users, called a Honeypot:

http://www.sitepoint.com/honeypot-captcha/

Several years ago I started using the popular Securimage CAPTCHA which worked reasonably well at the time, however:

1. It was really annoying to users
2. To make it mildly accessible you had to disable most of the techniques for fooling computers
3. It was complicated to install initially

Fairly recently I learned that the very jarring user-input CAPTCHA's were becoming a bit tired and old-hat, and that the Honeypot was a fairly reasonable, no-nonsense approach, and I've had tremendous success implementing these in sites. The great thing is that they're easy to implement, and you don't have to rely on someone else's popular (and therefore easily hackable) code - and with some JS knowhow you can improve on the concept by building forms with JS, adding server side session challenges and more. So long as the web bot isn't rendering the page and using that as its mechanism for filling out forms, you're save - and most malicious bots go for the direct approach by reading the raw HTML.

Good luck!