I've always brushed off free traffic as inefficient because of the amount of time that you need to put into it, but I met a guy yesterday that has been funding his paid campaigns with free traffic - he makes about $3-4k a month just from "free traffic". I thought he was just bullshitting me until he showed me his stats.
Which brings me to why I'm posting this thread...
What's the most (per day) that you have made from free traffic? Meaning that you spent $0 getting that traffic.
How much time did you put into it?
How steady was the income and how long did it last?
What was the traffic source? (eg. Youtube... SEO... etc)