Of late, the “recommend this” script which I’d set up for the free Vastu book was getting hit in a big way by spambots. After much procrastination (and stupidly hoping they would just go away!) I finally pulled it down a couple of weekends ago. Now it’s back with some CAPTCHA protection.
It’s based on this “tell a friend” script that I found at digital point. Needless to say, it’s been heavily tweaked to conform to web standards and to behave exactly the way I want but, most importantly, it seems to have pretty solid security.
Edit: The link to digital point is now broken.