First $100: Amazon referral account. I set up a stupid website which had a referral link. Also, occasionally I'd post referral links to reddit and Facebook when the product I was linking was highly relevant to the conversation.

First $1,000: Haven't made it yet. My referral account got banned after I stupidly sent a referral link to a finance person at work who was ordering more RAM for my system and wanted to know exactly what to order.

Someone paid me $150 to rewrite a Perl script in Python.

Maybe one day I'll finish writing this game I haven't worked on in a while and reach $1,000 with that.