Over the years, Dave Oranchak has done some great research into the Zodiac Killer's ciphers. He's created two popular cipher analysis web applications (webtoy and cryptoscope) and collected a wealth of information related to the ciphers of the Zodiac Killer.
Recently, he started a new website that provides analysis and discussion regarding the ciphers of the world's most enigmatic serial killer, as well as consolidated access to Dave's previous contributions. The new website is:
If you're at all interested in the Zodiac Killer's ciphers, I encourage you to check it out and spend some time in the various parts of the site. Based on his previous work, he's already got quite an impressive collection of content. And as we move forward, I'm sure he'll continue to add to the collection in interesting and meaningful ways.