Short and sweet: I've spent the past year or so cleaning up Stack Overflow answers that offered bad PHP security/cryptography advice and I feel like I've done as much as I can there.
https://meta.stackoverflow.com/questions/293930/problematic-php-cryptography-advice-in-popular-questions
Instead of scraping the bottom of the barrel, I'd like to look for places that more junior developers tend to congregate so I can help diffuse knowledge about security engineering and cryptography far and wide.
What are some other places worth focusing on?