you mentioned extra change in your question, so i am assuming you are looking for something in your spare time that you can do when you have availability?
have you considering blogging for dollars? or writing articles as a freelancer? webdesign projects here and there? i guess it comes down to what your strengths and interests are. what do you enjoy doing? there is a need for pretty much any skill today and there are resources set up (i.e. elance) to allow you to work part time.
some time back i was looking for something similar and i ran into paid surveys. i started playing around with them and fast forward to today i have developed it into a passive business. it has taken the power of a serious recruitment effort but the rewards have been phenomenal for me. i had not dreamt of such results. if you want to read a bit about my experience you can visit the link i have below.
or is there a topic/niche you are interested in? have you considered developing a website around that niche? i have also been successful earning extra money developing a site around certain niches. revenues come mainly from google adsense and affiliate marketing. it is quite a common way to earn extra money today. i have a link below about this as well if you want to learn more.
bottom line is that figure out what you enjoy doing and then find existing proven business models and apply it to what you like doing. just like your quote indicates, if you love what you do then success will come to you.
good luck and let us know what you choose and how it goes!
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