Brian keeps a diary of his hobby -- finding changes. According to his nicely kept weblog Change Is Good, he has found $464.73 since January 19, 1998. He apparently has some diligence and some luck because two out of three days he can find a coin or more.
Of course, there is a cost of being frugal, and there is a cost of finding changes. Assuming Brian spends two minutes a day finding changes, his hobby is actually rewarded at around $7/hour. This reminds me that we are not doing all things for money, and oftentimes a hobby will bring more happiness than money.
My hobby is to keep my little corner at PFBlog.com. Yes, I am running ads; I cannot disclose how much I earn because it is against the policy of the Google's Adsense program but I can only say if I need to monetize my hundreds of hours putting to this site, my hourly payout will be less than $1. But still, I find a lot of fun running the site and continuing my journey.