I know of one very interesting example - I got into my current line of work, which I've been in for the past 7 years, because of one conversation on a message b

I know of one very interesting example - I got into my current line of work, which I've been in for the past 7 years, because of one conversation on a message board where I was complaining about the difficulty of finding work and got advice as to a specific place to look. That throwaway comment from a stranger has had an incredibly significant impact on the course my life has taken, something that person will never know. Given the butterfly effect, it seems reasonably likely that the greatest change I'll make to how the future develops will be a similar throwaway comment in a forum like this one.