Thanks to a complete lack of material in this niche, the site (http://pengapplicant.ca) gets a decent amount of organic search traffic given the niche size (2k page views per month) and I make about $15/month in Adsense. Recently I was also contacted by someone who sells materials for the application and exam and have become an affiliate for them. It's only been one month, but i've already made one referral which netted me $100. So passive income on this after hosting costs is probably $220-ish and will be more in 2017 hopefully with more affiliate sales. Obviously very small potatoes, but I never set out to make any money for this and it looks like now it will at least cover my yearly professional dues ;)
To be honest, the best part is the messages I get from people saying how I helped them get their license. That's a much nicer feeling than the $.
That said, the PE exam was a breeze for me (took computer engineering exam). I'm slightly horrified that the failure rate is 50%.
In my jurisdiction (Ontario, Canada), if you graduate from an accredited engineering school and gather the requisite work experience, there is no technical exam, it is the same ethics and law exam for all disciplines (PPE or Professional Practice Exam). Documenting your work experience is probably the most work-intensive task as they want you to lay out what you did and how it qualifies as engineering in great detail. Probably the biggest reason for my traffic is that I published my (anonymous) experience record, since real life examples of this document are nearly impossible to find on the web. For the exam, I basically studied for the better part of a week. It's a 3 hour exam where your answers are typically paragraphs or pages long. I get the sense that some engineers struggle with it due to language issues more than anything else.