personally i find my niche from several ways :
1. Read anything in internet, not only seo / money making forum but also general forum, articles etc. Just open your mind and you can find it. People everywhere need some help or looking for something..
2. My friend request, some of my friend is asking me to solve their problems .. i will always looking at google about their problems and sometimes i know a way to make it better or find something good buried deep on page 5+ of google search ..
3. doing a niche research, Find general niche ( 10 or more ) , find several spesific niche on each general niche( usually 10 or more spesific niche ), do some knowledge research to filter those niche, doing some competition research to filter it more ( not every high competition and/or high result on google is bad , sometimes its good as long as all page 1-2 result not have my spesific keywords i will still try to compete with them ) and in the end i will have 1-3 niche idea that i can use ... and after that i will repeat the whole process ..